Every year, around 45 million people get the flu in the US. This year, it was less than 2,000. It’s an unprecedented low for flu season, and it’s a tribute to how well social distancing measures have worked—though they didn’t stop COVID-19 entirely, influenza has virtually disappeared. This year’s case counts were two-thirds lower than the lowest year previously on record.
But this time next year, we’ll almost certainly be much closer to that 45 million mark—some experts warn it could even be a particularly bad year, though it’s unclear which way the pendulum will actually swing.
One reason for this is that we’ve had an entire year of being relatively unexposed to the influenza virus. It’s possible that this could make for lower immunity levels and therefore more infections, though one expert told USA Today that the lack of exposure shouldn’t matter.
More importantly, the dearth of flu cases means we don’t have much data about which strains are circulating—and that could make choosing the annual flu vaccine more challenging. Each year, experts at the World Health Organization (as well as public health officials in each country) convene to discuss and analyze the data about which influenza viruses are most problematic this year. They then select which strains should be included in the vaccine. Most flu vaccines today are quadrivalent, meaning they contain four different strains. Fewer circulating strains could actually make the vaccine more effective, because it means less genetic diversity. The closer the currently circulating flu strains are to each other, the better the chances of producing a flu vaccine that works well against most of the strains.
But there’s also a chance that the genetic diversity amongst flu strains hasn’t actually decreased, it’s just that we’re testing fewer people for flu and therefore not collecting as much data. That could make our annual jab less effective in the end if we accidentally choose a strain that’s well-represented in the data but not actually very prevalent in the real world.
This is, unfortunately, one of those situations in which we won’t know until we know. What we can tell for sure is that the measures we took in the past year are extremely effective against the influenza virus. And while no one expects the world to shut down each winter, it’s worth remembering that there are some key practices we can continue to implement to prevent some of the 20,000-plus flu-related deaths each year. Washing your hands, staying home from work when you’re sick, wearing a mask if you’re feeling ill, and getting the annual flu shot can all help keep flu cases low without sacrificing your social life. We’re all pandemic-weary, but those simple measures don’t have to be exhausting. We just need to make them a part of the new norm.