• Get your flu shot

    Much attention is being paid to the rise of preventable outbreaks of whooping cough, measles, and other diseases that can be prevented, at both the individual and population level, through immunization. Quite rightly, misguided anti-vaccine activists such as Jenny McCarthy have been sharply criticized for their harmful and inaccurate statements which undermine public health.

    If you read TIE, you probably agree with these criticisms. So here’s a personal question: What about your own flu shots?

    Influenza kills thousands of Americans every year. This is an important issue. Yet surprising numbers of educated people who shake their heads at false claims of a link between vaccines and autism don’t get their flu shots—one of the simplest and most effective steps you can take to help yourself, those close to you, and the broader community.

    Flu shots are quite safe. They are among the most carefully-studied medical interventions around. Precisely because these are administered to millions of people every year, medical and public health experts know more about their side-effects. I was reminded of the value of this epidemiological enterprise when I grabbed the July 11 issue of JAMA, which included two articles exploring the safety record of the H1N1 vaccine.

    In the first study, Pasternak and colleagues  performed a nationwide cohort study examined birth outcomes of 53,432 Danish infants delivered between November 2009 and October 2010. These authors found no increase in risk for major birth defects, preterm birth, or fetal growth restriction among infants exposed in-utero to the vaccine.  As an accompanying commentary discusses, this study and others suggest that flu shots are safe when administered during pregnancy. Such findings are especially welcome because pregnant women have specific vulnerabilities to flu itself.

    A second study, by De Wals and colleagues, assessed a sensitive and legitimate issue: Guillain-Barré syndrome. These authors assessed the risks following vaccination of an estimated 4.4 million residents of Quebec. These authors did find elevated risks 4-8 weeks after vaccination. Yet the estimated excess risk of Guillain- Barré was extremely small: about two additional cases for every million doses, with no no indication of increased risk among people younger than 50 years of age.

    No, flu shots don’t confer perfect immunity. Their effectiveness varies across people, across flu strains, and across years. They do markedly reduce your individual flu risk. That’s quite enough incentive to hit Walgreen’s next flu season at lunch hour. The contribution to herd immunity, and to protection of the elderly and the immune-compromised may be more important. Child vaccination data from Japan suggest that vaccines prevented between 37,000 and 49,000 deaths every year–about one death for every 420 children vaccinated. That’s not a trivial number.

    So before you cluck your tongue at Jenny McCarthy, make sure to get your own seasonal vaccines. This is a real responsibility of citizenship in a modern society.

    • It’s true, the risk of flu shots is very low. But then again, their effectiveness may not be all that great for those who actually need them.

      Here are three vital questions that have yet to be answered: Are flu shots effective in those who need them (the elderly, immune compromised, young children)? And are they needed in those in whom they appear to be effective (healthy people)? Finally, what percentage of the healthy population would need to be vaccinated in order to reduce transmission to the point that it would benefit those who are truly vulnerable? If you search the flu literature, there are hundreds of studies, but none addresses these fundamental and crucial issues.

      The degree of uncertainty raises an important public health debate. Are we spending money wisely when we launch massive public health campaigns aimed at getting people to go out and get their flu vaccine? I’m not convinced. Most of what what we call flu isn’t actually caused by flu virus, and naturally flu vaccine can’t protect against those infections. Maybe the money we spend trying to get people to get their flu shots would be better spent trying to get them to wash their hands and sneeze into their elbows, measures that reduce the transmission of all upper respiratory viral infections, including influenza.

    • “If you search the flu literature, there are hundreds of studies, but none addresses these fundamental and crucial issues. ”

      Huh? The post you are responding to specifically answered those questions: one life saved for every 420 children vaccinated.

      (There have been a lot of articles on herd immunity in Science Magazine. I vaguely recall reading useful overview articles there. So that would be a place to start. I’d guess Nature would have covered it as well.)

    • Very useful comments (both of you).

    • The study (already over 10 years old) you cited seems rather weak with the potential for many confounding factors. Have the Japanese reinstated the vaccination program and was there an immediate drop in mortality?

      I personally have not had a flu shot since I retired 10 years ago and have not had the flu. When working I did get flu shots and was often ill with some sort of bug. I think the importance of vaccination is way oversold.

      Studies on safety are not reassuring to me because they look for acute reactions and not long term health effects. I believe that there has been no demonstrated decrease in all cause mortality for seniors in areas of high vaccination.