I’ve been writing about flu vaccines since I experienced the flu myself in 2013. During that rather unfortunate and painful couple of weeks, I was prompted to review the state-of-the-state research with regard to influenza vaccination to answer the question for myself: should I get a flu vaccine?
“The perception that current vaccines are already highly effective in preventing influenza is a major barrier to game-changing alternatives. Indeed, hundreds of influenza vaccine efficacy and effectiveness studies have been conducted since the 1940s, and vaccine efficacy in healthy adults of 70% to 90% is frequently cited. However, the preponderance of the available influenza vaccine efficacy and effectiveness data is from studies with suboptimal methodology, poorly defined end points, or end points not proven to be associated with influenza infection.” [Osterholm, M.T.,The Compelling Need for Game Changing Influenza Vaccines. 2012 ]
Osterholm went on to be quoted in the New York Times,
“We have over-promoted and overhyped this vaccine. It does not protect as promoted. It’s all a sales job: it’s all public relations.”
And now research recently published in the journal Clinical Infectious Diseases demonstrates that the more years one receives the influenza vaccine, the less efficacious it becomes.
Looking at 5 years of historical vaccination data, vaccine effectiveness for influenza A in individuals with NO prior vaccine history was 65% (95% CI 36%-80%) as compared to individuals with a frequent vaccination history, where effectiveness was reduced to 24%. Results were similar in Influenza B: 75% and 48% vaccine effectiveness, respectively. Results were similar for both children and adults.
If you regularly receive the flu vaccine, efficacy is reduced to about 24%.
Why?
It’s not well-understood, but one idea is “original antigenic sin” that is, pre-existing memory responses to previous vaccinations can preferentially expand at the expense of new (de novo) responses to the current vaccine. This appears to be greatest when viruses have some antigenic relatedness and are antigenically complex, which generally fits the annual influenza picture.
In the quest for a universal flu vaccine (that is, a one-time long lasting flu vaccine), research published this month in Science Translational Medicine by Andrews, et al. looked specifically at B cell response to 2009 H1N1 vaccine over time. They found that those with lower titer levels of preexisting antibodies were more likely to generate a good response to the more conserved hemagglutinin stalk region of the virus (see image below). People with higher levels of preexisting antibodies were more likely to generate antibodies to the variable hemagglutinin head region (the head region mutates, the stalk is conserved).
The higher amount of preexisting head antibodies prevented or blocked production of stalk antibodies, thereby reducing or eliminating the universal vaccine effect.
Further, the study also showed that production of the hemagglutinin stalk antibodies can cross-react with insulin and DNA. This is particularly concerning if the goal of the universal vaccine is to generate high numbers of stalk antibodies- promoting autoimmunity would be a very real concern, and has been suggested with previous influenza vaccines. [As an aside, check out this retracted study on cross reactivity between H1N1 Influenza A epitope and hypocretein/orexin in narcolepsy…]
Osterholm, a scientist not afraid to speak the plain truth, and director of the Center for Infectious Disease Research and Policy, isn’t convinced, apparently, that a universal vaccine is coming anytime soon.
[But all is not lost. FxMed can help, and once again, for the 2015-2016 flu season, I am reprinting below our clinic’s TOP TIPS for preventing and treating influenza.]
Image from: Viruses 2014, 6(8), 3159-3180
http://cid.oxfordjournals.org/content/early/2014/09/29/cid.ciu680.full