Last year we saw hardly any cases of flu because COVID-19 precautions – masking, distancing, business closures and travel restrictions – significantly stymied opportunities for the influenza virus to spread from person-to-person. And that may have some people wondering: Do I need to bother getting a flu shot this year?
In short: Yes. Getting immunized against flu this year may be more important than ever. The influenza virus is primarily spread through respiratory droplets from someone infected with the virus (possibly before they even have symptoms) to someone who is susceptible because they don’t have immunity to the current strain. There are two primary types of immunity: Natural immunity and vaccine-induced immunity.
Every year in early fall, manufacturers release updated influenza vaccines thought to cover the strains that experts believe are most likely to circulate in the coming flu season. These vaccines induce antibodies to protect against the flu. In a typical year, about half the U.S. population gets a flu shot, though far more people are eligible and should get immunized.
Fortunately, natural immunity also helps protect the population, since not everyone gets vaccinated.
Natural immunity happens when you’ve previously had the strain of flu that is circulating, or a close analog. Your immune system remembers and knows to fight any similar future strains it encounters. We, as a population, lost some of our natural immunity when the flu, for all intents and purposes, never took off last year. That means that this year more people – particularly young children who may never have encountered the influenza virus in their lives – have less or no natural immunity than in a typical flu season.
My colleagues and I recently ran two independent computer models to predict what the flu might do this year. In a worst-case scenario, up to 400,000 more people than we’d see in a normal year would contract the flu so badly that they required hospitalization. If this happens at the same time we’re experiencing a COVID-19 surge – perhaps from a new variant – the U.S. health care system could be overwhelmed.
But this ‘twindemic’ scenario is not inevitable. Our models also showed us that if more people than usual get the flu shot – if we can boost vaccination rates to 75% of the U.S. population – then we can avoid an excessive surge in flu hospitalizations.
The flu shot is safe and effective. As with nearly everything in life, it isn’t perfect. Some people who are vaccinated will still contract the flu, but those people may be less likely to need hospital care.
Take the flu shot this year. Take it for yourself, your family, your neighbors and your community. And take it for our health care heroes, who really don’t want to see you in their hospitals this winter.