The difference between the almost right word & the right
word is really a large matter – it's the difference between
the lightning bug and the lightning.

Mark Twain

December 24, 2014

About Flu Shots

This is an easy year to pick on the flu vaccine. The Centers for Disease Control and Prevention has said this year’s vaccine may not work as well as in earlier years because many of the viruses in circulation are not the ones vaccine manufacturers were anticipating for the 2014-2015 flu season.

I probably put that inelegantly so here’s a direct quote from the media release CDC put out on December 4, 2014. “Increasing the risk of a severe flu season is the finding that roughly half of the H3N2 viruses analyzed are drift variants: viruses with antigenic or genetic changes that make them different from that season’s vaccine virus. This means the vaccine’s ability to protect against those viruses may be reduced, although vaccinated people may have a milder illness if they do become infected.” See (

So, if this year’s flu vaccine may not be very effective, how effective is it in a good year? We don’t really know, says the CDC. The agency provides a useful discussion of the flu vaccine on its website, under the heading Vaccine Effectiveness - How Well Does the Flu Vaccine Work?

For starters, the CDC says “how well the flu vaccine works (or its ability to prevent flu illness) can range widely from season to season. The vaccine’s effectiveness also can vary depending on who is being vaccinated.” The agency adds the flu vaccine does not work as well in children younger than two years or adults older than 65 years.

CDC goes on to say “during years when the flu vaccine is not well matched to circulating viruses, it’s possible that no benefit from flu vaccination may be observed. During years when there is a good match between the flu vaccine and circulating viruses, it’s possible to measure substantial benefits from vaccination in terms of preventing flu illness. However, even during years when the vaccine match is very good, the benefits of vaccination will vary across the population, depending on characteristics of the person being vaccinated and even, potentially, which vaccine was used.”

The careful reader would have picked up on the agency’s candid acknowledgement of the vaccine’s limitations, even during a good year. To repeat the question: How well does the vaccine work in years when there is a good match between the vaccine and circulating viruses? “Recent studies show vaccine can reduce the risk of flu illness by about 60% among the overall population during seasons when most circulating flu viruses are like the viruses the flu vaccine is designed to protect against,” the CDC says. Your mileage may vary if you are younger than two years or older than 65 years.

It is not news the flu vaccine is not particularly effective. In 2012, scientists at the Center for Infectious Disease Research and Policy at the University of Minnesota released a report which concluded flu vaccinations provide only modest protection for healthy young and middle-age adults, and little, if any, protection for those 65 and older.

“Moreover, the report’s authors concluded, federal vaccination recommendations, which have expanded in recent years, are based on inadequate evidence and poorly executed studies,” the New York Times reported.

“We have over-promoted and over-hyped this vaccine. It does not protect as promoted,” says Dr. Michael T. Osterholm, director of the Minnesota center and a well-known expert.

Two years earlier, The Cochrane Collaboration, an international network of experts that evaluates medical research, concluded flu vaccines decrease symptoms in healthy adults under 65 and save people about a half-day of work on average, but that they do not affect the number of people hospitalized and have minimal impact in seasons when vaccines and viruses are mismatched.

“It also concluded that the vaccines appear to have no effect on hospital admissions, transmission or rates of complications. A separate Cochrane review on vaccines for the elderly determined the evidence was so scant and of such poor quality that it could not provide guidance,” the New York Times added.

Yet, every year we are given the same simplistic message: Protect yourself. Get the flu shot.