Fewer people got the flu shot last season—and that may be why it was one of the deadliest

By now you’ve probably heard that last year’s flu season was one of the worst on record. Preliminary estimates suggested new heights for hospitalizations and deaths. The Centers for Disease Control recently released more final numbers showing that yes, the 79,400 people who died and the 959,000 hospitalizations and the staggering 48.8 million who simply caught the flu were the highest since the 2009 H1N1 pandemic. And there’s now one more thing we know: fewer people got the flu shot than ever recorded.

Most years, the majority of people in the U.S. fail to get vaccinated for the flu. Rates have hovered just above 40 percent for years, but for the 2017-18 season only 37.1 percent got the shot. Alicia Fry, chief of epidemiology and prevention in CDC’s influenza division, told The Washington Post that this unusually low coverage might have contributed to the severity.

But while 37.1 percent is a paltry number across the entire population, the story changes a bit when you break it down by age group. The people at highest risk for getting the flu and for having serious complications, those over 65 or below 18, get vaccinated at significantly higher rates than the national average. It’s still not enough—we’d really need to get to 70 percent coverage as a population to achieve herd immunity—but the data can point us toward those people who still aren’t getting their flu shots.

The answer shouldn’t be that surprising. Healthy adults between the ages of 18 and 49 have by far the lowest vaccination rates. Many studies have tried to identify the barriers that keep people from getting their annual shot, but few of the results will surprise you either: people don’t think the shot is effective; people think they’re not likely to get the flu anyway; people intend to get the shot, but forget or don’t have the time or don’t have the money.

It may surprise you to know, however, that the CDC only started recommending that healthy adults get the flu shot at all in February 2009. And it may also surprise you to hear that, at least in a 2012 survey, less than half of all U.S. adults were aware that they were supposed to get vaccinated. A more recent study from 2017 found that, although 62.3 percent of adults knew there was some kind of recommendation to get the flu shot, only 19.6 percent could correctly identify who was supposed to get it. The correct answer is, by the way, that everyone over the the age of six months should get the flu shot (barring those with autoimmune issues whose doctors specifically recommend against it).

Research on strategies to increase vaccination rates suggests that, though many people who intend to get the flu shot may fail to, people who simply learn about the value of a flu shot are more likely to get one. So here are our best arguments to convince you:

It’s true that the flu shot is not 100 percent effective, but it does decrease your risk of getting the most severe symptoms, and those are the ones that can kill you.

The best time to get your flu shot is October. It takes about two weeks for your body to build immunity, so you should get the vaccination before the season really starts.

People with egg allergies can get the flu vaccine, though if you’re still nervous you can request an animal cell-based one instead.

Even if the shot doesn’t keep you from getting sick, it helps prevent you from spreading it to others who either can’t get the shot or are extra vulnerable. Your grandparents and newborn relatives will thank you for protecting them.

And finally, it is never too late to get your flu shot. The best time may have been yesterday, but the second best time is now.