A Deeper Look Into the Flu Vaccine and Its Importance to Public Health
By some estimates, the flu has exchanged as much as 25% of its genome in the last 50 years.
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 two 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.
These experts are the real deal and have access to decades of experience and reams of cutting-edge, up-to-the-minute data. So, it's not like they're just spinning that big wheel on The Price is Right and hoping for the best.
But we're not quite Raymond Babbitt counting cards in a casino, either. Every year, the Centers for Disease Control and Prevention (CDC) estimates the flu vaccine's effectiveness based on the odds that a patient admitted to the hospital with flu symptoms during the previous flu season had received that season's vaccine.
The results have been good, but not great; in the last 10 years, the adjusted effectiveness has varied between 19% and 60%, with an average efficacy of approximately 45%.3 A substantial part of this shortcoming stems from our inability to perfectly predict which viral strains are coming down the pipe.
As a consequence, the literature is bursting at the seams with ingenious schemes and complicated methodologies for improving the accuracy of our predictions. Some of these attempts might bear fruit, and many others certainly will not — but, at this juncture, and years away from their potential implementation, it's impossible to know which is which. Again, prediction is hard.
There is a sure-fire way for us to gain an upper hand with the flu virus, though. It's simple: get more people vaccinated. Last year, we managed to vaccinate approximately 59.3% of children and 41.7% of adults.4 These numbers aren't outliers; they've actually been more or less flat for a few years. But, imagine if we were able to get the adult vaccination rate up to, say, that of children?
Even the most conservative estimates suggest that that would result in tens of thousands of fewer flu-related hospitalizations annually. Better yet, what if flu vaccines were mandatory for all school-age children? The savings on direct healthcare costs alone would easily reach into the tens of millions.
Obviously, drastically improving the vaccination rate won't be easy. It will require a much greater commitment to preventative public health on the part of our governments and, possibly, a sea change in the general public perception of the importance and efficacy of flu vaccination. But, the health and economic benefits leave no doubt that it's a goal worth pursuing. And if none of that works? We can always try public shaming.
- Vaccine Effectiveness - How Well Does the Flu Vaccine Work? Centers for Disease Control and Prevention. Updated February 15, 2017. www.cdc.gov/flu/about/qa/vaccineeffect.htm. Accessed July 6, 2017.
- Gorman RM. Predicting flu's future, one year at a time. BioTechniques. Updated March 3, 2014. www.biotechniques.com/news/Predicting-Flus-Future-One-Year-at-a-Time/biotechniques-350767.html?service=print#.WWOh5fnyuUk. Accessed July 7, 2017.
- Influenza (flu). Centers for Disease Control and Prevention. Updated June 26, 2017. www.cdc.gov/flu/index.htm. Accessed July 7, 2017.
- Flu vaccination coverage, United States, 2015-16 influenza season. Centers for Disease Control and Prevention. Updated September 29, 2016. www.cdc.gov/flu/fluvaxview/coverage-1516estimates.htm. Accessed July 7, 2017.