This year’s flu season could be a rager. Shots can help.

As summer winds down and gives way to cooler weather, people are once again bracing themselves for an uptick in COVID-19 cases—viruses like SARS-CoV-2 prefer colder seasons. But there’s another virus looming that’s all-too-familiar: influenza.

Now, two new study preprints, neither yet peer-reviewed, suggest that last year’s drop in flu cases could lead to a high resurgence of flu this season due to lower immunity against influenza across communities. A 25 to 50 percent increase in flu vaccinations this year, one study says, could prevent that upswing.

Last year was a record low for the flu. The US Centers for Disease Control and Prevention (CDC) report that the 2020-2021 flu season yielded just one child death by the flu—an incredible dip from the previous low of 37 (during the 2011-2012 season) and the 2019-2020 record high of 199. But public activity in the US today is significantly higher than this time last year, when the majority of adults were still not vaccinated and many were spending their time masked or at home. As people slowly return to old routines and habits, health experts are worrying about a resurgence of the flu, and urge people to get a flu shot if they can.