One of my favorite blogs is one done by Vincent Rancaniello. He makes diseases and viruses, well fun!
His latest blog discusses new studies out on the influenza vaccine. He notes that since 1967 there have been 5,707 studies on how well influenza vaccine protects against infection. Many of them did not properly assess whether individuals were infected with influenza, leading to overestimation of the protective effect of vaccines. In many studies a four-fold increase in serum hemagglutinin antibodies were used to confirm infection. Immunization also increases these antibodies, making it difficult to confirm viral infection.
Lets cut to the chase… The results of 31 studies show that the trivalent inactivated influenza vaccine is overall 59% effective in individuals 18-65 years of age. That means of every 100 individuals immunized, 41 will be susceptible to influenza. Ugh!!! That number is far too low – it should be above 90%. The infectious, attenuated vaccine fared better – it is overall 83% effective but only in children 6 months to 7 years of age. It was not significantly effective in protecting individuals 18-49 years old.
This study sends a strong message that better influenza vaccines must be developed. Remember, we are still making vaccine likes it is 1950. New vaccines with improved clinical efficacy and effectiveness are needed to further reduce influenza-related morbidity and mortality.
This study will likely be used by folks who feel it is unnecessary to be immunized against influenza as an argument against getting a flu shot. The researchers however say that frankly “it’s better than nothing”, however it is quite clear that is not a ringing endorsement. Alas it isn’t hard to imagine that the results of this study will likely lead to a decline in influenza immunization rates in the US.