The H1N1 vaccine is here, and after wide-spread media panic, the government trying to get as many vaccines out as possible, and plenty of anti-vaccine rhetoric flying back and forth, people are getting a bit anxious about it. For some of my friends, I’m the only one with even a superficial knowledge of medicine (I’m a biochemist and immunologist, not a doctor), so I suppose it’s natural that I’ve had a couple people call or e-mail me about what I think of the vaccine and whether or not they should get it. I’ve also seen a few people post links on facebook that I’ve tried to respond to, but I thought I should give a more thorough account here.

First, let me state my position without equivocation: Get vaccinated! I already got my seasonal flu shot, and as soon as the H1N1 “swine flu” vaccine becomes available, I’ll get that one too.

Getting the flu sucks, and vaccines are effective. They are the reason we have nearly eradicated small-pox and polio from the face of the earth. Flu is a bit different – it’s highly mutable and getting immunity one year does not protect you every year (more on that later). So why are people against vaccines? There are several reasons that I have run into, and I will try to address them each in turn.
Objection 1) Vaccines are not effective:
A great example of this is an article a friend linked to in The Atlantic. This is probably one of the most credible sources I have ever read regarding the flu vaccine (and please note that it says nothing about the safety of vaccines), but it’s still ambiguous. These are the claims article makes that I can identify:

a) Research about the effectiveness of the flu vaccine directly preventing deaths in the most vulnerable populations (the very young and the very old) is not as solid as is seems.

Yet some top flu researchers are deeply skeptical of both flu vaccines and antivirals. Like the engineers who warned for years about the levees of New Orleans, these experts caution that our defenses may be flawed, and quite possibly useless against a truly lethal flu. And that unless we are willing to ask fundamental questions about the science behind flu vaccines and antiviral drugs, we could find ourselves, in a bad epidemic, as helpless as the citizens of New Orleans during Hurricane Katrina.

There have been thousands of studies pointing to the efficacy of vaccines in general, and probably hundreds about the flu vaccine in particular. This article points to a few recent “meta-studies” that suggest that previous attempts to gauge the effectiveness of the flu vaccine may have misinterpreted the data. Essentially, they allege that the observed reduction in deaths among the elderly between those who received the vaccine and those that did not are more attributable to the differences between people likely to get the vaccine and those who aren’t (ie. poor people are less likely to get the vaccine, and poor people are more likely to die from influenza, which will skew the numbers in favor of those that received the vaccine).

There are plenty of scientists who disagree with this data, but this kind of debate is healthy in science, and I’m convinced that after a few arguments and counter-arguments have been made, we will land on a consensus that is closer to the truth. But let’s assume for the moment that the article is correct and current studies about the direct prevention of death in the elderly by the flu vaccine are completely wrong and the flu vaccine is not effective. In this circumstance, it’s even more important for people my age to get the vaccine. We know that vaccines work (see: polio, measles, small pox etc), and we know that the flu vaccine works, at least in young, healthy individuals. So it’s even more important that I don’t get sick, so that I don’t pass on the illness to someone’s grandmother. Put differently, I’m contributing to herd immunity. Furthermore, this year’s swine flu pandemic is not limiting itself to killing the very young and very old, it’s disproportionally killing people ages 25-49.

b) Placebo-controlled studies would be useful in determining the actual efficacy of the vaccines.
I’m sure this is completely true, and I would support it, but I’m a bit more callous than most doctors regarding research on people, and if you believe the vaccine is effective, it is unethical to withhold the vaccine from people that you think would be helped by it. Still, in the absence of placebo-controlled studies, one can still imagine taking an epidemiological approach taking into account socioeconomic differences mentioned above to get a clearer, less biased picture. In any case, I agree fully with this premise, but it still doesn’t argue against getting the vaccine.

c) Anti-viral medications are not as effective as they claim to be, and leads to drug-resistance.
If this is true (and it’s generally accepted that at least the second part is), then again it’s even more important to get as many people vaccinated as possible. If we can’t treat flu, then the only thing we can do is prevent it, and the single most effective way to prevent a viral infection is with a vaccine.

All in all, the main thrust of this article is that our current strategies against the flu may not be as effective as we believe, but there’s nothing there to suggest that vaccines are not the answer. Maybe we need a better way to make vaccines, so that we can make them more rapidly and not simply attempt to predict the dominant strains a year in advance. Maybe we need a better way to administer them or a way to target epitopes of the virus that don’t change as much. I agree with all of these sentiments, but I don’t think there’s any evidence here that vaccines are not the best strategy to protect people against the flu.

Objection 2) Vaccines are dangerous
I should point out up front that this claim is patently false, and I will attempt to address the main concerns that people tend to point to. The only people that are in legitimate danger from the flu vaccine are people with egg allergies (the vaccine is manufactured in chicken eggs, and the immune system is burly enough that even trace amounts of egg proteins can cause severe reactions).

First, the most easily addressed, the fallacy of post hoc, ergo propter hoc. “There was this person that got a vaccine, and then a week later she got ‘x.'” A perfect example of this is an amazingly irresponsible story from some local news program.

Doctors say that she has a rare, one in a million neurological disorder that was triggered 10 days after getting a seasonal flu shot

The story is heartbreaking, but you’ll notice that no one draws any causal connection between the vaccine and the neurological condition. The sentence above might as well have read “Doctors say she got hit by a car 10 days after getting a seasonal flu shot.” Sometimes bad things happen to perfectly good people, and occasionally those bad things will follow within days or even hours of getting a flu vaccine. If it’s something medical, like a heart attack or a neurological condition, anti-vaccination people will point to it and say: “See, the vaccine is dangerous!” even though no one can point to any link, other than a temporal one, between the vaccine and the disease. For another great example, see the story of Natalie Morton, a 14 year old girl that died tragically less than 2 hours after receiving the vaccine for HPV. News outlets flipped out and started reporting that the vaccine had caused her death, only to find out after the autopsy that she had an undiagnosed cancer that had infiltrated her heart and lungs. Let me reiterate, countless studies have been done on the flu vaccine, and the only serious risks associated with the vaccine occur at rates significantly below you general risk for contracting and dying from the flu or flu-related complications.

Probably the most common objection is the toxins contained in vaccines, notably mercury, that people will claim causes autism in children and all kinds of other problems. While it’s true that some vaccines still contain a preservative called thimerosal which has mercury complexed with it, study after study after study has shown that the amount of mercury is well below toxic levels (you’ll get more mercury if you go out for sushi). For a longer (if that’s possible) and better written description of the autism question, check out this article in wired magazine.

Twelve epidemiological studies have found no data that links the MMR (measles/mumps/rubella) vaccine to autism; six studies have found no trace of an association between thimerosal (a preservative containing ethylmercury that has largely been removed from vaccines since 20011) and autism, and three other studies have found no indication that thimerosal causes even subtle neurological problems.

So, the TLDR version: GET THE VACCINE!! (unless you’re allergic to eggs). It’s not a panacea, even if everyone got the flu vaccine every year, we wouldn’t eradicate flu. There are limitations, to be sure, but the simple fact is that it works. And it’s SAFE, at least as safe as any medication you would be prescribed by your doctor. You will not get lead poisoning, you will not get autism, you will not get hit by a car (at least, not as a result of getting the vaccine, unless you get hit by lead car on your way to the clinic to get your shot). So ignore the fear-mongering, listen to the science, and go roll up your sleeve.


Misinformation abounds on the internet, but there are plenty of sites where you can get credible, science-based information on vaccines.
– The CDC has tons of links about the supposed controversies.
– For information about all things flu-related, check out the flu-wiki
– And for a more irreverent take on this and many other pseudo-science “controversies” check out  quackcast and the millenium project.