Public Health and Influenza: Why the Flu Vaccine is So Important
In the last 10 years, the adjusted effectiveness of the flu vaccine has varied between 19% and 60%, with an average efficacy of approximately 45%.
I'm not usually an advocate of public shaming, but it definitely has its place. My hospital, like thousands of others around the country, has made flu vaccination mandatory for staff and employees. When flu season rolls around, they hire an armada of bubbly public health soldiers who spend months chasing down the non-compliers.
Still, through what I imagine must be a combination of superhuman discipline and Green Beret-level evasive maneuvers, a few people manage to fall through the cracks each year. For these intrepid souls — who have apparently determined that they can't afford the 2 minutes and zero dollars required to get the shot — the hospital has determined that firing is too good a fate.
Instead, they're forced to come to work every day wearing a brightly-colored tag on their lanyard and masks covering half their faces. It might as well be a scarlet letter. When you pass one of these people in the hall, the polite thing to do is avert your eyes.
There's no question that flu vaccines, which contain deactivated non-virulent versions of specific strains of the flu virus, work. Vaccination lowers flu-related illness in children, the elderly, people with diabetes or cardiovascular disease, pregnant women, and even unborn babies.1 It keeps people in vulnerable populations from getting sick in the first place, and in people who do contract the illness it results in milder symptoms. It's a classic win-win-win. But, the flu hasn't made it easy.
By some estimates, in the last 50 years the flu has exchanged as much as 25% of its genome.2 This rapid-fire evolution is a perpetual source of consternation for the public health groups charged with designing the flu vaccine every year — and is only exacerbated by the 6-month lead-time required to manufacture a clinically significant volume of vaccine doses. The problem is superficially simple, yet devilishly complex: how do you predict what next year's flu will look like?
For starters, it helps that genomic modeling can tell us the precise composition of this year's flu. While we know that next year's edition won't look exactly the same because of the virus' high rate of genomic exchange, we can also be pretty sure that it won't look that much different, barring an unforeseen — and pretty catastrophic — antigenic shift.
But after that, it's a high-stakes guessing game. The World Health Organization (WHO) crams as many super-smart scientists as they can into a conference room for a few days, bombards them with data meant to enable them to forecast the virus' progression and then lets them argue for a while before coming out with a recommendation.