Health and Science News for Parents
Nov
24

It’s That Time Again: Separating Fact from Fiction about the Flu Vaccine

written by Tara Haelle

This post is co-published with NPR’s health blog Shots. Check out the story for updated information about this year’s flu shot from a CDC medical officer.

Once again, flu season is upon us — and so are all the misconceptions, excuses and worries that have kept so many people away from getting their flu vaccines. Plenty of people are fully informed about the flu vaccine’s safety and effectiveness and simply choose not to get the vaccine, as is their right (as long as they don’t work in healthcare settings where it’s required). But many others may have skipped the shot because they’ve bought into one of the many myths about the vaccine that always circulate with the influenza virus itself. Or perhaps they’ve read something unsettling about the vaccine that has a kernel of truth in it, but which has been blown out of proportion or misrepresented.

Of all the vaccines out there, the flu vaccine is unique in several ways: it’s the only one the CDC recommends for the entire (eligible) population every year, it has the most variability (and nearly always the lowest percentages) in effectiveness, and it has more tall tales told about it than Paul Bunyan. Much of the debunking and explaining you’ll find here is essentially the same as in past years’ posts, but a couple misconceptions have been rearranged, and I spent a bit more time discussing the evidence about potentially lower effectiveness of the flu vaccine in people who had gotten it the previous year.

Don't let bad information get in the way of making an important health decision.

Don’t let bad information get in the way of making an important health decision.

Another change you’ll find is that the “myths” are now concerns, phrased as questions. What’s up with that? I made that change for a couple reasons. One relates to the research findings that straight up stating myths and then debunking them can backfire, though this new approach doesn’t necessarily eliminate that risk. Another reason is that stating misconceptions declaratively implies an adversarial approach by the reader when, in reality, I hope and expect the majority of people reading this post genuinely have questions about the vaccine. So writing each one as a question better represents that spirit of inquiry.

Finally, I called these items “concerns” instead of “myths” because several of the issues discussed here are not outright “myths.” That is, some of these concerns originated from factual situations, but the details got gnarled and twisted along the way, or else the fact itself doesn’t have the implications people may expect it does. “Concerns” therefore better captures that each of these items is a legitimate concern for many people but is something that simply requires explanation, whether that’s an outright debunking or simply context and clarification.

One thing that needs a bit of clarification is last year’s vaccine’s effectiveness, as I discuss in the NPR Shots blog post that accompanies this one. The overall flu vaccine effectiveness last year was an uninspiring 23%, low enough to legitimately make you wonder why you bothered if you got the vaccine. But as I explain at NPR based on an interview with CDC influenza medical officer Lisa Grohskopf, the overall effectiveness doesn’t capture the effectiveness of each strain within the vaccine.

A poor match with the H3N2 strain — which caused the most illness and the most serious cases — was responsible for the lion’s share of that low number. Meanwhile, the match between the vaccine strains and the virus strains for B viruses, which circulated the most toward the end of the season, was good enough that the vaccine was closer to 60% effectiveness for those strains. This year, changes to the H3N2 strain for the vaccine should boost the effectiveness and offer a better showing than last year’s lousy run, according to Grohskopf.

With that info out of the way, let’s get to the flu vaccine concerns, with two important notes. First, for those who prefer to do their own research, I’ve provided all my sources in the hyperlinks. More than half of these go directly to peer-reviewed research articles, and a fair number go to the Centers for Disease Control and Prevention or the World Health Organization.

Second, but very important: I am a science journalist but not a medical doctor or other health care professional. I’ve compiled research here to debunk common misconceptions and clarify common concerns about the flu vaccine. This post does not constitute a recommendation from me personally to each reader to get a flu vaccine. You should always consult a reliable, trusted medical professional with questions that pertain specifically to you. For the CDC recommendations on the 2015-2016 flu vaccines (including information on which vaccines pregnant women, the elderly and children under 2 should *not* get), please consult the CDC flu vaccine recommendations directly. There are indeed people who should *not* get the flu vaccine.

To make it easier to navigate, I’ve listed all 31 concerns at the top followed by the factual information below it. They hyperlinked facts will jump to that explanation. I use “flu shot” and “flu vaccine” interchangeably to refer to any type of flu vaccine, including the nasal vaccine.

Concern #1: Can getting the flu vaccine give you the flu or may you sick?
Fact: The flu shot can’t give you the flu.

Concern #2: Do I really need to get the flu vaccine this year if I got it last year?
Fact: For now, a new flu shot each year is still recommended.

Concern #3: Could getting the flu vaccine make it easier for me to catch viruses, pneumonia or other infectious diseases?
Fact: Flu vaccines reduce the risk of pneumonia and other illnesses.

Concern #4: Isn’t the flu shot just a “one size fits all” approach that doesn’t make sense for everyone?
Fact: You have many flu vaccine options, including egg-free, virus-free, preservative-free, low-dose, high-dose and no-needle choices.

Concern #5: Can the flu shot cause death?
Fact: There have been no confirmed deaths from the flu shot.

Concern #6: Aren’t deaths from the flu exaggerated?
Fact: Deaths from influenza range from the lower thousands to tens of thousands each U.S. flu season.

Concern #7: Aren’t the side effects of the flu shot worse than the flu?
Fact: Influenza is nearly always far worse than flu vaccine side effects.

Concern #8: Don’t flu vaccines contain dangerous ingredients such as mercury, formaldehyde and antifreeze?
Fact: Flu shot ingredients do not pose a risk to most people.

Concern #9: Shouldn’t pregnant women avoid the flu shot or only get the preservative-free shot? Could the flu vaccine cause miscarriages?
Fact: Pregnant women are a high risk group particularly recommended to get the flu shot. Fact: The flu shot reduces miscarriage risk. Fact: Pregnant women can get any inactivated flu vaccine.

Concern #10: Can flu vaccines cause Alzheimer’s disease?
Fact: There is no link between Alzheimer’s disease and the flu vaccine; flu vaccines protect older adults.

Concern #11: Don’t pharmaceutical companies make a massive profit off flu vaccines?
Fact: Vaccines comprise a tiny proportion of pharma profits. That makes it possible for them to continue making them in the event of a pandemic.

Concern #12: Flu vaccines don’t really work, do they?
Fact: Flu vaccines reduce the risk of flu.

Concern #13: But flu shots don’t work in children, do they?
Fact: Flu vaccines reduce children’s risk of flu.

Concern #14: Can flu vaccines cause vascular or cardiovascular disorders?
Fact: Flu shots reduce the risk of heart attacks and stroke.

Concern #15: Can vaccines can break through the blood-brain barrier of young children and hinder their development?
Fact: Flu vaccines have been found safe for children 6 months and older.

Concern #16: Will the flu vaccine cause narcolepsy?
Fact: The US seasonal flu vaccine does not cause narcolepsy.

Concern #17: Can the flu vaccine weaken your body’s immune response?
Fact: The flu vaccine prepares your immune system to fight influenza.

Concern #18: Can’t the flu vaccine cause nerve disorders such as Guillain-Barré syndrome?
Fact: Influenza is more likely than the flu shot to cause Guillain-Barré syndrome.

Concern #19: Can the flu vaccine make you walk backwards or cause other neurological disorders like Bell’s palsy?
Fact: Neurological side effects linked to flu vaccination are extremely rare (see Concern #18), but influenza can cause neurological complications. Fact: The flu shot has not been shown to cause Bell’s palsy.

Concern #20: Don’t people recover quickly from flu since it’s not really that bad?
Fact: Influenza knocks most people down *hard*.

Concern #21: Can people die from the flu even if they don’t have another underlying condition?
Fact: Otherwise healthy people DO die from the flu.

Concern #22: Can people with egg allergies get the flu shot?
Fact: People with egg allergies can get a flu shot.

Concern #23: Can’t I just take antibiotics if I get the flu?
Fact: Antibiotics can’t treat a viral infection.

Concern #24: Since I got the flu last time I got a flu shot, that means it doesn’t really work for me personally, right?
Fact: The flu shot cannot guarantee you won’t get the flu, but it reduces everyone’s risk.

Concern #25: But I don’t need the shot since I never get the flu, right?
Fact: You can’t predict whether you’ll get the flu.

Concern #26: Can’t I protect myself from the flu by simply eating right and washing my hands regularly?
Fact: A good diet and good hygiene alone cannot prevent the flu.

Concern #27: Won’t getting the flu simply make my immune system stronger?
Fact: The flu weakens your immune system while your body is fighting it and puts others at risk.

Concern #28: If I get the flu, why won’t just staying home prevent me from infecting others?
Fact: You can transmit the flu without showing symptoms.

Concern #29: Can having a new vaccine each year make influenza strains stronger?
Fact: There’s no evidence flu vaccines have a major effect on virus mutations.

Concern #30: Isn’t the “stomach flu” the same thing as the flu?
Fact: The “stomach flu” is a generic term for gastrointestinal illnesses unrelated to influenza.

Concern #31: Is there any point in getting a flu shot if I haven’t gotten one by now?
Fact: Getting the flu shot at any time during flu season will reduce your risk of getting the flu.

Concern #1: Can getting the flu vaccine give you the flu or make you sick?

Fact: The flu shot can’t give you the flu.

It’s perhaps the most common misconception, but it’s not biologically possible to catch an illness from the inactivated vaccine. Does that mean no one gets sick right after getting a flu shot? Of course not – some people statistically will get sick after getting the vaccine. They might have caught that bug before getting the shot, and it took a few days for symptoms to appear, or they could have coincidentally caught it after the shot. Or, they might have caught the bug *at* the doctor’s office or pharmacy while waiting to get the vaccine. But they didn’t get the flu or any other illness from the vaccine. The flu shot takes two weeks to confer protection, and it takes 2-5 days to incubate a flu virus. A person who does come down with the flu within a week of getting the shot was already infected when they got the vaccine.

Even with the live vaccine in the nasal spray, the weakened virus cannot cause the flu in you. However, it is theoretically possible to “shed” the virus after receiving the live vaccine, thereby infecting others, though no serious cases have been reported of this occurring. It’s primarily a theoretical risk and not something that should influence which vaccine you choose to get. I got the nasal vaccine last year, and the pharmacist explained that sneezing directly on my 6-month-old in the hour after getting the shot could technically transmit the virus, but it was highly, highly unlikely, and even then, the inactivated virus I sneezed onto him would be unlikely to cause illness.

Aside from an actual illness caused by a virus or bacteria, it is certainly possible for people to just feel “under the weather” or “unwell” from the side effects of the flu shot. As the immune system ramps up to produce antibodies against those influenza strains, you might experience a headache, nausea, a low fever, etc. These are normal responses to the vaccine in some people. You might feel “sick,” but you have no fallen ill from a pathogen in the flu shot, nor did you catch the flu from the shot.

Concern #2: Do I really need to get the flu vaccine this year if I got it last year?

Fact: For now, a new flu shot each year is still recommended.

This is one of those concerns with a less clear-cut answer, but the shortest answer is “almost certainly, at least this year.” The CDC still recommends the flu shot each year, but scientists are still puzzling out how annual shots influence risk because the flu virus is so darn tricky. As I noted in the article accompanying this piece at NPR’s health blog Shots, infectious disease reporter Helen Branswell reported at Stat recently that getting a flu shot every year might reduce its effectiveness in warding off the flu. This finding isn’t entirely new. A 2014 study suggested that “past history of vaccination” might also have played a role in lower effectiveness against the 2011-2012 flu season’s H3N2 A strain. Another in 2014, by the same author of the study Branswell reported on, had similar findings.

But it’s a study way back in 1999 that actually offers a possible explanation for these counterintuitive findings: “the antigenic distance hypothesis.” That is, the more different a particular vaccine’s strains are from the previous year, the more effective the vaccine is likely to be (assuming the vaccine strains match the circulating strains that year). But vaccine strains that are more similar to the previous year’s vaccine strains — such as last year’s H3N2 A strain, identical to the strain in the 2013-2014 season’s vaccine — may end up less effective, and we did see very low effectiveness last year because of the H3N2 strain.

In short: different strains from year to year, good; same strain year after year, maybe not as good — but only compared to people who got the shot during the current year and not the year before. (Compared to people who didn’t get the vaccine at all, getting the vaccine one year even after getting it the previous year still appears to reduce risk for the current year.) Confused yet?

Let’s look specifically at this year, since that’s the year that matters right now. Typically, the strains included in each year’s flu vaccine change from one year to the next, based on the WHO’s educated guess on which strains are most likely to circulate. That’s actually the reason for getting a new shot each year: to be sure your body is making antibodies for the strains most likely – the experts think – to be floating around. As it turns out, this year’s vaccine contains two new strains and two strains identical to last year’s shot. The H1N1 this year is the same as in last year’s shot, but, crucially, the H3N2 strain this year is very different from the one in last year’s shot — and H3N2 is the strain that typically gives us the most trouble. (It’s usually more common and causes more severe illness.) The B strain in the trivalent shot this year is also new. The B strain in the quadrivalent shot is the same as that in last year’s quadrivalent shot:

  • an A/California/7/2009 (H1N1)pdm09-like virus (same as last year)
  • an A/Switzerland/9715293/2013 (H3N2)-like virus (significantly different from last year’s A/Texas/50/2012 strain)
  • a B/Phuket/3073/2013-like virus (different from last year’s B/Massachusetts/2/2012-like strain)
  • B/Brisbane/60/2008-like virus (in quadrivalent vaccines only; same as last year)

So, what does all this mean? It means even if the flu vaccine in 2014-2015 was less effective for people who also got it in 2013-2014 (something still up for debate), those same people should still get the 2015-2016 vaccine because two strains are very different from past vaccines’ strains. Plus, getting the vaccine any year still reduces your risk of catching the flu compared to people who do not get the vaccine at all.

For those intellectually curious, why might similar strains year after year reduce effectiveness? Well, if your body has already encountered a particular pathogen or a look-alike (like what’s in vaccines), it doesn’t exactly ramp up into action as quickly because it should already have some antibodies. The immune response is more like, “Meh, you again? I already got you covered.” That blunted response to a vaccine with a similar strain means less build-up of antibodies. (It’s the same reason children shouldn’t get the measles before 8-12 months. Before then, they still have enough of their mother’s measles antibodies that they don’t respond as well to the vaccine.)

Add to that previous research that flu antibodies against one particular strain have the potential to last a loooooong time, at least if you had the flu itself. A 2008 study found that people who survived the 1918 flu pandemic still had antibodies for that specific strain decades later. But that was the flu, not the seasonal flu vaccine, stimulating the body’s antibody production (and it was only against that *one* strain, of which there are thousands, and we rarely get a blast-from-the-past strain once it’s mutated).

Aside from all of this, it’s worth noting that the flu vaccine is manufactured with the intent to protect you for only one season, and we know some vaccines’ immunity wanes (sometimes even ones that aren’t supposed to). In fact, the flu vaccine’s effectiveness has been shown to wane, particularly among older adults. On the other hand, a very recent multi-year study found similar levels of protection from both the current year’s flu vaccine and the previous year’s vaccine (but those who benefitted most from the shot were those who hadn’t had one in the past five years). So you may have some protection against the H1N1 and the quadrivalent Brisbane B strains this year if you got the shot last year, but you won’t have any protection against the more worrisome H3N2 strain or the Phuket B strain this year.

Concern #3: Could getting the flu vaccine make it easier for me to catch viruses, pneumonia or other infectious diseases?

Fact: Flu vaccines reduce the risk of pneumonia and other illnesses.

For some reason, this misconception has been circulating a lot this season, but there is no evidence to support it. For one thing, catching the flu will weaken your immune system while you’re sick, during which it’s easier to become ill from other bugs. But more importantly, pneumonia is among the most common complications to occur as a result of a flu infection, so getting the flu shot *reduces* your risk of pneumonia, a leading cause of death among those who die from influenza complications. In any case, scientists have actually studied this question and found in a 2013 study that people are no more likely to get other (non-influenza) viral infections after they’ve gotten the flu vaccine.

Concern #4: Isn’t the flu shot just a “one size fits all” approach that doesn’t make sense for everyone?

Fact: You have many flu vaccine options, including egg-free, virus-free, preservative-free, low-dose, high-dose and no-needle choices.

This one couldn’t be further from the truth. While there are definitely some people who should not get any flu vaccine, the CDC table of 2015-2016 influenza vaccines offers people more options than ever before in choosing the vaccine that’s best for them. Two years ago, I got the trivalent injection (with thimerosal) while pregnant. Last year, I got the quadrivalent live nasal vaccine because I wasn’t pregnant and I got it with my 4-year-old son. This year, my son and I got the quadrivalent shot together, and you can see in the video that he did great with it.

This year includes a total of 16 different options (including different brands) in six different categories. There’s the good old-fashioned trivalent (three-strain) shot and the four-strain quadrivalent shot, both available with or without the preservative thimerosal, which prevents contamination from fungi or bacteria in multi-dose vials. Another standard quadrivalent option is the needle-free quadrivalent nasal vaccine, but this is a live vaccine that should not be administered to pregnant women, children under age 2, adults over age 49, and immune-compromised or egg-allergic individuals. For needle-phobic people who can’t get the live vaccine, the trivalent jet injector is available.

One of two changes this year is that the intradermal shot is now quadrivalent; this low-dose shot uses a short needle that goes into the skin instead of the muscle. The other change is that the recombinant vaccine this year is now available for all adults over age 18. The recombinant vaccine does not use the flu virus or eggs during its manufacturing and is therefore ideal for those with egg allergies. The other egg-free option is the cell-based vaccine, made from viruses grown using mammalian cells. Finally, those over age 65 can get the high dose shot. Whatever you want, find a flu vaccine provider and see if they have your preferred vaccine.

Concern #5: Can the flu shot cause death?

Fact: There have been no confirmed deaths from the flu shot.

People can die after getting the flu shot. That doesn’t mean they died because of the flu shot. In fact, no confirmed death from the flu shot has ever been reported, but you will see stories pop up now and then claiming otherwise. For example, in late November 2013, news outlets reported a young Utah man’s death that his mother attributed to the flu vaccine. But it’s pretty unlikely that this man’s tragic death was caused by the flu vaccine, as explained here. It’s not impossible, but there is no evidence for the assertion.

It is possible – very, very, very, very rare but technically possible – to die from the flu vaccine if you have a severe allergy to gelatin, but such anaphylactic reactions to the gelatin in a vaccine only occur to about 1 in every 2 million people, and they don’t typically die. Pointing out that people have died after getting a flu shot is little different than pointing out that some people have gotten into car accidents right after buying ice cream sundaes. Few people would assert the sundae caused the car accident. Dying after getting a flu shot doesn’t mean the flu shot killed you any more than dying after downing an eggnog means the eggnog killed you.

Concern #6: Aren’t deaths from the flu exaggerated?

Fact: Deaths from influenza range from the lower thousands to tens of thousands each U.S. flu season.

While some have claimed that flu deaths are exaggerated each year, they’re taking advantage of the fact that it’s incredibly difficult to accurately track how many people die because of the flu. First, states aren’t required to report influenza deaths. Second, not everyone who dies due to a respiratory illness is tested for the flu, and not everyone who is gets an accurate result. Third, and most importantly, people tend to die from complications of the flu, not the flu itself. (Or, as one friend put it, no one dies from falling off a building. They die from deceleration when they hit the ground.) People can also die from a pre-existing condition, such as heart disease, because their body is weakened from fighting flu.

In the U.S., an estimated 53,826 deaths occurred from flu and pneumonia combined in 2010 and 53,667 died in 2011, making combined influenza and pneumonia the eighth leading cause of death that year. But only about 8.5% of pneumonia deaths are flu-related, so those numbers cannot tell us precisely how many died only from just the flu and its complications. Flu deaths actually vary wildly from one year to the next, depending on the dominant strains (H3N2 is linked to the most deaths). A 2010 study by the CDC found they’ve ranged from a low of 3,349 deaths in 1986-87 to a high of 48,614 deaths in 2003-04. The average is probably about 23,600 deaths a year.

Concern #7: Aren’t the side effects of the flu shot worse than the flu?

Fact: Influenza is nearly always far worse than flu vaccine side effects.

The most common side effects of the flu vaccine are aches, itching, fatigue, headache, fever, hoarseness, sore or red and itchy eyes and a cough, plus soreness, redness or swelling where the shot was given. Young children may, in rare cases, develop a high fever (a febrile seizure) that can result in a short seizure, not causing long-term damage. (Febrile seizures are not uncommon in young children generally.) The most serious risk is an allergic reaction, possible in approximately 1 out of every 1 to 2 million doses. In the H1N1 vaccines, Guillain-Barré syndrome may be an increased risk for 1 to 2 of every 1 million doses (see Concern #18), though it’s many times more common from influenza itself.

The flu itself, as noted above, is much more serious and can cause death.

Concern #8: Don’t flu vaccines contain dangerous ingredients, such as mercury, formaldehyde and antifreeze?

Fact: Flu shot ingredients do not pose a risk to most people.

Single dose-shots of the flu vaccine and the flu vaccine nasal sprays do not contain any mercury compounds. The multi-dose flu shot does contain a preservative called thimerosal, which breaks down into 49% ethylmercury and used to prevent bacterial contamination of the vaccine container. Ethylmercury, as I’ve discussed before, is processed differently by the body than methylmercury, the neurotoxin that can build up in the body and is found in fish. (Keep in mind the difference a letter can make in chemistry: methanol is anti-freeze while ethanol is a Chardonnay.) Ethylmercury is made of larger molecules that cannot enter the brain and exits the body in a week or so.

There is no danger in receiving a vaccine with thimerosal – they’re given all over the world and it’s been extensively studied, even for cumulative effects on children over several years. If you want to avoid it anyway, or if you’re allergic to thimerosal, you can simply request a flu shot without the preservative.

Formaldehyde is used in safely small amounts in manufacturing several flu vaccines (Fluarix, FluLaval, Agriflu and Fluzone) to inactivate the virus so it cannot cause disease. Trace amounts might remain in the final vaccine. It is not in other influenza vaccines (Afluria, FluMist and Fluvirin). Formaldehyde, as I’ve written before, also occurs naturally in fruits and vegetables: about 2,000 mcg of formaldehyde in an average banana and anywhere from 8600 to 13200 mcg in a pear. Yet the amount of formaldehyde in flu vaccines ranges from 5 µg per dose (Fluarix) to 25 µg per dose (FluLaval) to 100 µg per dose (Fluzone). For those concerned that the formaldehyde in flu shots is injected rather than consumed, consider that the human body produces formaldehyde for a variety of functions, such as making amino acids, and has about 2,600 mcg of formaldehyde per liter of blood. So the tiny amount from the flu shot – which does not stick around and accumulate – will make little difference to your body.

The claim of antifreeze being in vaccines appears to come from the use of octylphenol ethoxylate (Triton X-100) (in Fluzone) or octoxynol-10 (Triton X-100) (in Fluarix) since this name looks similar to polyethylene glycol. Polyethylene glycol is one component of antifreeze but not antifreeze itself, just as water is a component of antifreeze. But polyethylene glycol isn’t Triton X-100 anyway. Triton X-100 is a splitting agent used to break up the virus components, and it’s been shown to be safe.

Some people may have allergies to flu vaccine ingredients, such as gelatin, thimerosal or antibiotics. See Concern #22 for more on this. Find out more about specific components of flu vaccines here or, for Fluzone in particular, see my “What’s Inside” piece in the October 2014 issue of Wired Magazine. Remember, however, that ONE LETTER can make a huge difference in what you’re talking about.

Concern #9A:  Shouldn’t pregnant women avoid the flu shot?

Fact: Pregnant women are a high risk group particularly recommended to get the flu shot.

Actually, the flu shot is one of the most important things a pregnant woman can get as part of her prenatal care. I got mine while pregnant two years ago, and the CDC recommends that all pregnant women without medical contraindications get one. The flu shot is safe for pregnant mothers, and even after their child is born, mothers who got the flu shot while pregnant have provided their babies with a bit of extra protection against acute respiratory infections. They also may reduce children’s risk of other conditions, such as bipolar disorder, associated with prenatal influenza exposure. And, moms who get the flu shot also offer their babies some protection against the flu from birth, even if they plan to breastfeed. For much more information (and research) about getting the flu shot while pregnant, check out my post specifically focused on flu vaccines during pregnancy.

Concern #9B: Could the flu vaccine cause miscarriages?

Fact: The flu shot reduces miscarriage risk.

Not only does the flu shot not cause miscarriage, this non-pharma-funded study in the New England Journal of Medicine actually shows that the flu shot *decreases* the risk of a miscarriages/stillbirths in pregnant women, not least because having influenza itself during pregnancy is linked to miscarriages. Interestingly, the flu shot can even reduce women’s risk of other birth complications, such as a preterm birth or an underweight baby, though it’s not clear whether this is a real effect or simply that healthier people tend to get the shot and tend to have fewer complications. For much more information (and research) about getting the flu shot while pregnant, check out my post specifically focused on flu vaccines during pregnancy.

Concern #9C: Shouldn’t pregnant women only get the preservative-free shot?

Fact: Pregnant women can get any inactivated flu vaccine.

The inactivated flu vaccine, with or without the preservative thimerosal, is safe for pregnant women, exits the body quickly and has not been shown cause developmental problems, neuropsychological conditions or any other problems in the fetus, short-term or long-term. I discussed thimerosal in greater detail above at Concern #8. (Bonus side note: Even though ethylmercury and methylmercury are quite different, it’s worth noting that even a pregnancy diet high in fish, which may expose a woman to more methylmercury, has not been found to have an effect on children’s development.) For much more information (and research) about getting the flu shot while pregnant, check out my post specifically focused on flu vaccines during pregnancy.

Concern #10: Can flu vaccines cause Alzheimer’s disease?

Fact: There is no link between Alzheimer’s disease and the flu vaccine; flu vaccines protect older adults.

This myth is even addressed on the Alzheimer’s Association website, where they note the 2001 study showing a *reduced* risk of Alzheimer’s among those who had received flu vaccines, the polio vaccine and the tetanus and diphtheria vaccines. In fact, the risk for developing Alzheimer’s was half as much for those receiving these vaccines. This misconception originated with a quack named Hugh Fudenberg who has no evidence for the claim.

Meanwhile, seniors are at high risk for flu complications and death and are recommended to get the flu vaccine each year, specifically the high-dose flu vaccine, since it offers greater protection for adults aged 65 and older, according to research. The live vaccine is not recommended for those over 65, but the intradermal flu vaccine is now available for this age group. (Side note: some worry about aluminum in vaccines causing Alzheimer’s — except that flu shots don’t contain aluminum and aluminum does not cause Alzheimer’s.)

Concern #11: Don’t pharmaceutical companies make a massive profit off flu vaccines?

Fact: Vaccines comprise a tiny proportion of pharma profits. That makes it possible for them to continue making them in the event of a pandemic.

There is no question that pharmaceutical companies are for-profit companies taking in billions and billions of dollars. Making money, however, does not mean one is immoral by default. Car seat manufacturers turn a profit, but that doesn’t mean we refuse to buy car seats on principle. That said, there have been plenty enough shady dealings, lawsuits, investigations and other such incidents to support a healthy suspicion of Big Pharma and its motives. But vaccines simply don’t offer enough revenue to make a difference here.

If pharmaceutical companies didn’t make a profit off vaccines, they wouldn’t manufacture them, leaving us without any flu vaccines. Keeping this production line going also means ensuring vaccines are available in the occasional years when a pandemic occurs. But vaccine profits are still a drop in the bucket compared to profits from medications for chronic conditions such as high blood pressure and mental illnesses.

The top three flu vaccine manufacturers – Sanofi Pasteur, Glaxo SmithKline and Novartis – pulled in about $3.1 billion from flu vaccines in 2013. Yep, that’s billions. But total pharmaceutical companies revenues last year were nearly $1 trillion – making the bulk of flu vaccine revenue only about 0.3% of total revenue. For those big three companies, flu vaccines comprise about 4.5% of total annual revenue. (Meanwhile, cholesterol-lowering drugs such as statins raked in $35 billion back in 2011.) For an even more in-depth look at these numbers, check out Skeptical Raptor’s post on Big Pharma profits from flu vaccines. He’s run the numbers and made it clear that flu vaccines just aren’t profitable enough to justify some grand conspiracy.

Meanwhile, the recommendations for vaccines come from public health organizations such as the CDC and similar public health, government and academic institutions across the world. Unless you think all those countries’ governments and public health officials are involved in a huge conspiracy or money-making scheme with Big Pharma (and if you think that, read this), then the fact that vaccines offer a profit to pharma companies isn’t a reason not to get vaccinated. In fact, influenza itself is quite costly, costing the US about $4.6 billion annually in direct medical costs and as much as $87 billion annually in all costs.

Concern #12: Flu vaccines don’t really work, do they?

Fact: Flu vaccines reduce the risk of flu.

Flu vaccines are not 100% effective. (Actually, no vaccine is 100% effective.) But they do reduce the risk of catching the flu even if they cannot eliminate the risk. And there are tons of studies showing this (and yes, many of these are not funded by Pharma). Unfortunately, the effectiveness of the flu vaccine varies quite a bit from year to year, and it’s among the less effective vaccines compared to ones such as the measles-mumps-rubella vaccine, whose effectiveness for measles is in the high upper 90%s. (The more people who get the vaccine, though, the better herd immunity is and the more effective it can be.)

There are a couple things to keep in mind about the effectiveness of the flu vaccine that vaccine researcher Jessica Atwell has explained. First, the flu vaccine has historically protected against only three strains each year (though the four-strain vaccines are becoming increasingly more common), but there are many more strains circulating each year. The World Health Organization make educated guesses by February about which strains will be circulating later that fall: some years their algorithms for picking the strains are better than others. Last year, they didn’t do so hot, but even last year’s lousy effectiveness of 18%-23% saved lives. The WHO did pretty well during the 2013-2014 season. Of more than 5,600 influenza viruses characterized that year, 99.8% of the H1N1 viruses were the strain in the vaccine that year, 95.3% of the H3N2 viruses were the vaccine strain, and 70.3% of the influenza B viruses were the vaccine strain. Another 29.4% of the influenza B viruses were the strain included in that year’s quadrivalent vaccine.

Yet even in the years when their estimates fall short, the flu shot is worthwhile: a meta-analysis looking at 34 randomized, controlled trials across 47 flu seasons found that even when the strains in the flu vaccine do not match the strains circulating that year, the flu vaccine offered a measure of protection against the circulating strains.

Next, the effectiveness of the flu vaccine varies for different age groups, partly because of the way the immune system ages. “Generally speaking, your immune system peaks in early adulthood and goes downhill from there – hence less than ideal efficacy of standard flu vaccines in the elderly,” Atwell said. (Though, again, the high-dose flu vaccine shows better effectiveness in the elderly in an August 2014 study in NEJM.) Yet even studies showing low overall effectiveness — this one found anywhere from 33 to 100 adults need to be vaccinated each year to prevent one case of the flu — still show a reduced risk of the flu in vaccinated individuals. Coming at it from a different angle, another study estimated that vaccination prevented anywhere from 1.1 million to 5 million flu infections during each flu season over six years.

Just because the flu vaccine does not work 100% of the time for 100% of people does not mean it’s worthless or ineffective. Mosquito repellent is not 100% effective for 100% of people, but I’m going to guess that most people will still use it before venturing into the Amazon, or even going camping for a summer weekend. Here’s another analogy: If there is a 50% chance it’s going to rain, do you take along the umbrella even if it’s an inconvenience? Some do because they don’t want to get wet if it does rain. Some bring it, but it’s a bad storm and they get a little wet anyway. Others don’t bring the umbrella. The difference? If you don’t bring an umbrella, it’s just you getting wet, but by not getting yourself vaccinated, you potentially put others at risk for catching the flu from you, if you catch it.

The Holy Grail, of course, is a universal flu vaccine to provide protection against many or all influenza strains. It’s a goal that many flu vaccine researchers have been working toward for years, but there are many challenges to such a vaccine and success has been elusive.

Concern #13: But flu vaccines don’t work in children, do they?

Fact: Flu vaccines reduce children’s risk of flu.

As noted above, the effectiveness of the flu vaccine varies by age and by which vaccine (live or inactivated) a person gets, but there is no doubt that it offers some protection against the flu. As Melinda Wenner Moyer points out in this Slate piece, the live vaccine (FluMist) was previously found more effective for kids aged 2 to 7, up to 83% effective (meaning kids who get the vaccine are 83% less likely to get the flu than gets who aren’t vaccinated). To put that study’s finding in absolute number terms, 16% of unvaxed kids got the flu compared to 3.4% of those who received the live vaccine.

The nasal vaccine was also found to have higher effectiveness in a 2014 study and led to the recommendation last year that children aged 2 to 8 get the FluMist if possible. More recent data on the live vaccine, however, have not confirmed higher effectiveness for children, so it’s no longer the preferred recommendation by the CDC.

Even an (inactivated) shot that offers 48% effectiveness offers more protection than zero, though. Another review of the research found that, for children under 6 years old, one child would be prevented from contracting influenza for every six who were vaccinated with the live vaccine. For children over 6, one case of flu could be prevented for every 28 kids who received the inactivated vaccine.

Moyer also notes that the research on the effectiveness of the flu for kids aged 6 months to 2 years is weak, mostly because there isn’t much data available. (That’s based on a Cochrane review whose only data set on children under 2 was a study with 16 infants.) It’s true the data is thin, but it’s not entirely nonexistent, and newer research, such as the NEJM study on the nasal vaccine and this one in The Lancet, has come out showing flu vaccine effectiveness in kids since the Cochrane Review.

The CDC notes that one study found the flu vaccine to be 66% effective in preventing lab-confirmed influenza in children aged 6 months to 2 years old. (While this study did not find the flu vaccine to help prevent ear infections, others have found that.) Another study has found a good immune response to the vaccine among children (including infants). In another, focused specifically on children aged 9 months to 3 years, only 4% of vaccinated children under age 2 caught the flu compared to 12% of the unvaccinated children, for another finding of 66% effectiveness.

Concern #14: Can flu vaccines cause vascular or cardiovascular disorders?

Fact: Flu shots reduce the risk of heart attacks and stroke.

This is another myth that should be flipped on its head. There is no evidence that the flu vaccine causes vascular disorders. Meanwhile, the vaccine has been shown in multiple studies to reduce individuals’ risk of heart attacks, stroke and other cardiovascular events.

Concern #15: Can flu vaccines can break the “blood brain barrier” of young children and hinder their development?

Fact: Flu vaccines have been found safe for children 6 months and older.

There is no evidence that flu vaccines can hurt children’s development or that flu vaccines affect children’s neurovascular structure. A child’s blood brain barrier is formed in utero and is functional from birth in regulating what can and cannot pass into the brain. Researchers at Stanford University and the University of California – San Francisco discovered in 2010 that pericytes are required for blood-brain barrier development and that pericytes are present in the fetal brain. This research shows that an infant’s blood brain barrier is developed before birth. The physiology of the blood brain barrier and how it functions at that level of development make it highly implausible that any vaccine components could penetrate the barrier.

Concern #16: Will the flu vaccine cause narcolepsy?

Fact: The U.S. seasonal flu vaccine does not cause narcolepsy.

This is one of the few concerns rooted in some fact, though often misrepresented or blown out of proportion. Narcolepsy is a neurological disorder in which the brain in unable to regulate sleep-wake cycles. Several studies, first in Finland and then in other European countries, found and confirmed a link between narcolepsy and the 2009 H1N1 flu vaccine called Pandemrix, manufactured by GlaxoSmithKline Europe and used in several European countries (but not in the U.S. or Canada). It was not used before 2009 or since the 2009-2010 season, and no links to narcolepsy have been found for U.S.-manufactured H1N1 or seasonal flu vaccines. The CDC sponsored a study looking for any possible links between the 2009 H1N1 flu vaccines and narcolepsy and found no increased risk of narcolepsy.

One hypothesis for the European vaccine’s link to narcolepsy relates to an adjuvant called ASO3, an oil-in-water emulsion. Adjuvants are substances added to a vaccine to increase the body’s immune response to that vaccine; U.S. influenza vaccines do not currently contain adjuvants. Other possibilities for the narcolepsy risk include immune stimulation from the vaccine itself, immune activation from H1N1 infection or another infection present at the time, or a combination of these factors. It’s also possible the narcolepsy risk is related to the H1N1 virus itself, which could means the flu infection could increase the risk of narcolepsy — but these are all conjectures for now. Recommendations in Europe were initially revised for the vaccine and then Pandemrix was suspended after the evidence came to light. The increased risk was estimated at an additional 3 to 7 cases of narcolepsy for every 100,000 vaccinated children (the link was only seen in those under age 21).

Concern #17: Can the flu vaccine weaken your body’s immune response?

Fact: The flu vaccine prepares your immune system to fight influenza.

Vaccines do not weaken the body’s immunological responses or cause other infections. They actually strengthen the immune system, activating a response that leads to the production of specific antibodies against the disease the vaccine is designed to protect against. The immune system is like a muscle and vaccines are like the exercise. The vaccines train your immune system for a future attack just like exercise strengthens your muscles and makes you body stronger.  (The flu, on the other hand, does weaken your immune system while your body tries to fight it.)

Concern #18: Can’t the flu vaccine causes nerve disorders such as Guillain-Barré syndrome?

Fact: Influenza is more likely than the flu shot to cause Guillain-Barré syndrome.

Guillain-Barré syndrome (GBS) is an autoimmune disorder in which the immune system mistakenly attacks a person’s own nerve tissue, causing muscle weakness and sometimes temporary paralysis. The disorder affects approximately one person out of every 100,000 individuals. Causes are not well understood, though the disorder has been linked to viruses including cytomegalovirus, Epstein Barr and influenza (as well as the bacteria campylobacter).

This misconception, like the one about narcolepsy, is partly based on fact because the 1976 H1N1 flu vaccine was found to be linked to a higher risk of GBS that year – approximately 10 additional cases of GBS for every 1 million people vaccinated. Since then, GBS risk has probably been the single most studied adverse event from the flu shot in the history of flu vaccine research, and the majority of it has shown no increased risk with seasonal flu vaccinations. One study that investigated the risk of GBS from the flu shot among more than 30 million “person-years” (equivalent to 30 million people over a year or 1 million people over 30 years) found no increased risk for the flu shot. Based on numerous studies, the independent Institute of Medicine “concluded that there was sufficient evidence to reject an association between influenza vaccination and GBS.”

Another study specifically on the 2009-2010 H1N1 vaccine did find an increased risk of GBS — but not as high as the risk of GBS from the flu itself (or the risk of death from the flu). It found a risk of 1 additional case of GBS per every 1 million vaccinations and 17 additional cases of GBS for every 1 million influenza infections. That flu season, the H1N1 influenza killed about 280,000 worldwide (more than 12,000 of whom were in the U.S., which recorded 61 million H1N1 infections during 2009). Finally, one study did find a slightly higher risk – 1.6 cases of GBS per 1 million vaccinations – for seasonal flu vaccines and the H1N1, but this increased risk in seasonal vaccines has not been found in other studies.

All that said, if you have been previously diagnosed with GBS, as the CDC recommends, you should consult with your doctor before receiving a seasonal flu vaccine. You may end up being one of those the rest of us will need to protect through herd immunity.

Concern #19A: Can the flu vaccine can make you walk backwards or cause other neurological disorders?

Fact: Neurological side effects linked to flu vaccination are extremely rare (see Concern #18), but influenza can cause neurological complications.

Remember that bizarre case of the cheerleader who said she got a flu shot and then she could only walk normally backwards, not forwards? She claimed she had developed a neurological disorder called dystonia that was triggered by the flu shot. There were some pretty significant problems with her story, however: all the experts looking at videos of the young woman said her symptoms appeared “psychogenic,” which means they were psychological, not neurological, in origin. That doesn’t make them less real, but it means the flu shot didn’t cause them. In fact, epidemiologist Rene Najera looked up the girl’s case report in the Vaccine Adverse Event Reporting System (VAERS) and found this: “The admitting neurologist felt that there was a strong psychogenic component to the symptomology, and made a final diagnosis of weakness.” So even the physician who directly examined her concluded her symptoms were most likely psychological.

Excluding Guillain-Barré syndrome, which Concern #18 addresses above, there is no evidence that the flu vaccine can cause neurological disorders, but there is evidence that influenza can. In fact, children with neurological disorders or other neurodevelopmental conditions are especially encouraged to get the vaccine because they are at a higher risk of complications from influenza than other children. Almost half of the children who died from the flu during the 2009 season had underlying neurological disorders, such as epilepsy or cognitive dysfunction.

Concern #19B: Can the flu vaccine cause Bell’s palsy?

Fact: The flu shot has not been shown to cause Bell’s palsy.

One of the many conditions once thought potentially linked to the flu vaccine is Bell’s palsy, a condition of uncertain origins, though it’s been linked to a range of viral infections. It appears that one flu vaccine used in Switzerland during the 2000-2001 season might have been linked to an increased risk of Bell’s palsy (46 cases). An investigation of U.S. reports in the decade prior also appeared to show a risk, which led to a more in-depth study. That in-depth one found no increased risk, which a report from the independent Institute of Medicine found as well. In addition, a study looking specifically for Bell’s palsy risks in children after a flu vaccination found no increased risk. Sometimes it can be tough to separate cause from correlation and to determine whether two things that happen at the same time are related or coincidence — hence the reason for multiple studies.

However, it is important that adverse events occurring after any vaccine is given are reported to the Vaccine Adverse Event Reporting System (VAERS) so that researchers can follow up on conditions that are reported multiple times. It’s best that a doctor make the report since medically confirmed events are generally given better weight. This is how new associations, such as the narcolepsy link with the European 2009 H1N1 Pandemrix vaccine, are identified.

Concern #20: Don’t people recover quickly from the flu since it’s not really that bad?

Fact: Influenza knocks most people down *hard*.

Influenza is a serious illness. The symptoms are similar to other illnesses, so people often mistake milder illnesses for the flu. Some lucky folks do recover in a day or two, but most are down for a week or two, and complications can be life-threatening, especially complications in children. A recent study found that half the children hospitalized in Australia during the 2009 pandemic had previously been healthy with no underlying conditions. Not everyone gets a fever, but having the flu isn’t pleasant, especially given the minor side effects or low risks for serious side effects from the vaccine.

During the 2013-2014 season, more than 9,600 hospitalizations were reported as a result of laboratory-confirmed flu during the 2013-2014 season – but those are just lab-confirmed flu (many cases of the flu are never lab tested), and the reported cases represent only about 8.5% of the U.S. population. If we assume – in a very rough estimate – that flu hospitalizations are evenly distributed throughout the U.S., that means there were likely more than 113,000 hospitalizations from just laboratory-confirmed flu during the 2013-2014 season. Among adults aged 65 and older, 88 out of every 100,000 hospitalizations were flu-related. The next highest rates were for adults aged 50 to 64, who were hospitalized at a rate of 54 per 100,000 admissions, and children younger than 5 years old: 47 of every 100,000 hospitalization was flu-related. But even healthy young adults ended up in the hospital with flu: Almost two-thirds of the hospitalizations (60%) were adults between 18 and 64 years old.

Concern #21: Can people die from the flu even if they don’t have another underlying condition?

Fact: Otherwise healthy people DO die from the flu.

People die from the flu. Every year. This includes adults who are healthy up until getting the flu and it includes children with no underlying conditions (plenty of tragic stories here). In 2013, in fact, 90% of the children who died from the flu had not been vaccinated. The annual numbers of lab-confirmed flu deaths in children are not high, but they are potentially preventable. A study published in Pediatrics reported that 43% of the more than 800 children who died from the flu between 2004 and 2012 had no underlying medical conditions. Often, influenza might contribute to a death but not be listed on the death certificate if the individual died from complications of the flu, such as pneumonia. And in 2013-2014 in particular, the H1N1 strains of the flu hit healthy adults – the “young invincibles” – particularly hard. So yes, the flu can kill you. Even if you take vitamins, eat healthfully, exercise daily, drink water and practice good hygiene.

Concern #22: Can people with egg allergies get the flu shot?

Fact: People with egg allergies can get a flu shot.

First of all, as explained in Concern #4, there are a variety of flu vaccine options, including two manufactured without using eggs. The recombinant vaccine Flublok, available for adults over age 18, and the cell-culture-based vaccine Flucelvax, approved in 2012, are both egg-free. For children, or those in areas where one of these vaccines is unavailable, the American College of Allergy, Asthma & Immunology states clearly, “People with egg allergy are not at any additional risk of having a reaction when given the flu vaccine even though the vaccine may contain some amount of egg protein.” This statement is based on the evidence in their influenza vaccination recommendations (paywall), summarized here. This also refers to non-severe egg allergies, and the CDC has provided a helpful flowchart for those with egg allergies planning to get the flu vaccine.

Some other allergic reactions can occur with the flu shot. Some people are allergic to thimerosal and should get the preservative-free shot. Some people are allergic to antibiotics and should get flu vaccines without added antibiotics. (The antibiotic polymyxin is in Afluria and Flurvirin, for example, and Fluvirin also contains neomycin.) And in very rare cases – about 1 in every 1-2 million doses of all vaccines – individuals with severe allergies to gelatin can have an anaphylactic reaction. If you have an egg allergy that causes an anaphylactic reaction, ask your allergist to administer the shot.

Concern #23: Can’t I just take antibiotics if I get the flu?

Fact: Antibiotics can’t treat a viral infection.

Influenza is a virus. Antibiotics fight bacteria (anti = “against”; biotics = “of life,” referring to living bacteria). All the antibiotics in the world won’t help you fight off a flu infection. (P.S. Neither will essential oils; there is no evidence to support any essential oils curing the flu.) In fact, we really need to lay off the antibiotics anyway.

Concern #24: Since I got the flu last time I got a flu shot, that means it doesn’t really work for me personally, right?

Fact: The flu shot cannot guarantee you won’t get the flu, but it reduces the risk of catching it.

As noted further up, getting the flu vaccine does not guarantee you won’t catch the flu. It does reduce your risk of getting the flu, and some evidence suggests you might have a milder course of the illness than if you hadn’t been vaccinated. It’s also entirely possible that you catch a strain of the flu not covered in the vaccine.

Concern #25: But I don’t need the shot since I never get the flu, right?

Fact: You can’t predict whether you’ll get the flu.

Millions of people have never gotten into car accidents. They still wear seat belts and carry car insurance. I’ve never been struck by lightning. But if there’s a thunderstorm raging, I avoid standing outside in wide open fields. It’s estimated that 6%-7% of adults (pdf) and about 20% of children under 5 get the flu each year. The past is no indicator of whether you’ll end up in that percentage this year any more than flipping a coin to heads tells me what the next flip will be.

Concern #26: Can’t I protect myself from the flu by simply eating right and washing my hands regularly?

Fact: A good diet and good hygiene alone cannot prevent the flu.

Influenza is an airborne virus, so although hand-washing is important and can reduce your risk of becoming ill from germs in general, all the hand-washing in the world won’t guarantee you don’t catch the flu. Eating a healthy, balanced diet is also important, and certainly being healthy makes it easier for your immune system to fight off new infections. But simply eating well cannot magically prevent you from being exposed to the flu virus.

Concern #27: Won’t getting the flu simply make my immune system stronger?

Fact: The flu weakens your immune system while your body is fighting it and puts others at risk.

As noted above, your immune system is weakened while you’re ill from the flu. While your immune system may be strengthened after you recover against that particular strain or a (theoretical) future related strain, a vaccine primes your immune system to fight off influenza strains in the same way (without the week of fever, chills and vomiting). Additionally, if you catch the flu, you are contagious to others. Being vaccinated helps keep herd immunity levels higher in your community, especially protecting those who are weaker or cannot be vaccinated.

Concern #28: If I get the flu, why won’t just staying home prevent me from infecting others?

Fact: You can transmit the flu without showing symptoms.

I’m glad you’ll stay home, but there are two problems with this plan. First, you’re contagious before symptoms appear, so you could infect someone before you even know you’re sick. Second, you could catch the flu but remain asymptomatic – showing no symptoms. That’s lucky for you but not for those around you whom you could infect. It’s unlikely, but you’re still putting others at risk.

Concern #29: Can having a new vaccine each year make influenza strains stronger?

Fact: There’s no evidence flu vaccines have a major effect on virus mutations.

This concern is a challenging one to address succinctly without oversimplifying the science. The short answer is that current vaccines are not likely to create more dangerous variants of a flu strain.

Influenza virus strains are evolving and changing on a regular basis in two main ways: “antigenic drift and antigenic shift.” Drifts are small, gradual changes that happen all the time in response to environmental pressure and even within our own bodies. The influenza virus has a segmented genome: its genome is in eight parts which can randomly re-assort. When the virus infects an individual, it can “exchange” these gene segments and change within that one individual. Our own immune response can invoke a selective pressure on the virus that contributes to drifting, with or without a vaccine. If the virus didn’t change at all from year to year, the flu vaccine would never need to be reformulated each year (and that Holy Grail of a universal flu vaccine would be less elusive).

It is possible that a vaccine could be among the environmental pressures influencing antigenic drifts, but no more so than what already occurs in our own bodies and most likely to a lesser extent. No current evidence suggests that vaccines cause major changes in the virus, such as an antigenic shift. A shift is much more troublesome change, leading to a dramatically different strain that our immune systems are not usually prepared for. A shift is what happened with the 2009 H1N1, and it’s what happened with the Spanish flu epidemic in 1918-1919. That pandemic only lasted a year, but it was far worse than a typical flu season, killing an estimated 3% of the world population. (More on that pandemic in this book.)

Interestingly, some believe it’s possible that high levels of herd immunity could reduce antigenic drift. This researcher explains, “As herd immunity increases, we should expect to see more antigenic drift; however, if immunity is high enough to prevent the population-wide spread of the pathogen, the epidemic cannot take off and the virus does not evolve.” Regardless, scientists do not expect current vaccines to create more dangerous variants of a flu strain.

Concern #30: Isn’t the “stomach flu” the same thing as the flu?

Fact: The “stomach flu” is a generic term for gastrointestinal illnesses unrelated to influenza.

Ever heard someone talk about a bad case of the “stomach flu?” People refer to any number of gastrointestinal illnesses that way, but the “stomach flu” isn’t related to the actual influenza virus. It’s just sloppy use of language. Most people talking about the stomach flu have diarrhea and vomiting, but without the fever and aches, and that’s unlikely to be the real-deal flu.

Concern #31: Is there any point in getting a flu shot if I haven’t gotten one by now?

Fact: Getting a flu shot at any time during flu season will reduce your risk of getting the flu.

Flu season continues well into January and February, not really petering out until late March or April, and flu vaccines tend to be available throughout that time. It only takes two weeks for your immune system to make the antibodies that offer protection, so it’s basically never too late to get the flu shot until flu season is over.

 

Please ask questions, provide new information, etc. in the comments. However, any comments which include inaccurate information posing as “warnings” or “countering” accurate info will be deleted. I encourage debate but not the dispersal of misinformation.

If you’ve read the alarmist “Should I Get the Flu Shot?” post from “Food Babe,” here’s a great, in-depth debunking of that piece.

Special thanks to the extensive research for this post goes to Kathy McGrath, Nathan Boonstra, Jessica Atwell, Rene Najera, Amber Bickford Cox, Karen Ernst and Emily Willingham.

 

 

 

 

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2 Responses to “It’s That Time Again: Separating Fact from Fiction about the Flu Vaccine”

  1. Susan

    The insert on the flu vaccine contradicts some of these “facts.” Bell’s Palsy has been reported as a side effect as well as Guillain Barre.

    • Tara Haelle

      Package inserts are required to list all adverse events that have occurred after the administration of a flu shot during clinical trials, regardless of whether that adverse event was known to be caused by the vaccine. In multiple subsequent studies, researchers determined that Bell’s palsy is not caused by the flu shot. Guillain Barre, however, remains a tiny possible risk.

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