The last two flu seasons in the U.S. were mercifully mild—one of the few silver linings of the pandemic, as COVID-19 mitigation measures likely also prevented many cases of influenza.
But our luck may run out this year. Australia, which often serves as an (imperfect) predictor of what’s to come for the U.S., has had its worst flu season in half a decade this year, CNN reports. Flu season also started early in Australia this year, another possible harbinger of what’s to come in the Northern Hemisphere.
Dr. Alicia Fry, chief of the epidemiology and prevention branch within the U.S. Centers for Disease Control and Prevention’s (CDC) influenza division, cautions that “if you’ve seen one flu season, you’ve seen one flu season”—meaning the virus is unpredictable and guesses about it aren’t always accurate. “Whether it will be a severe season or a mild season, or what to expect, or what viruses might circulate—that we really just don’t know,” Fry says.
Nonetheless, there are some factors that could set up the U.S. for a more serious flu season this year, says Dr. Brandon Webb, an infectious disease specialist at Utah’s Intermountain Medical Center. Flu season severity varies quite a bit from year to year, depending on factors including immunity in the population and which influenza strain is circulating. “Individuals who get influenza the year prior probably carry over some incomplete or partial immunity,” Webb explains. Since few people got infected during the past two flu seasons, “we’re looking at globally, and especially in the U.S., record low community immunity levels to influenza.”
The relaxation of COVID-19 mitigation measures like masking, social distancing, and remote working and schooling could also allow influenza to spread as it did before the pandemic, Fry says.
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The possibility of a heavy flu season colliding with the still widely circulating SARS-CoV-2 virus is concerning for the health care system, Webb says. “If we have even a moderate-to-high influenza season that generates 300,000 or 400,000 hospitalizations and are also having to deal with a fall or winter COVID wave, that could put a strain on hospital systems around the country,” he says.
The best thing for individuals to do is get vaccinated sooner rather than later, Fry says.
On Sept. 1, federal health officials recommended that people 12 and older get a new bivalent COVID-19 booster, which targets currently circulating Omicron variants. The updated shots are available to adolescents, teenagers, and adults who are at least two months out from their last COVID-19 vaccine dose (though some experts recommend waiting a bit longer). Meanwhile, the CDC recommends getting a flu shot by the end of October.
“If a person wants to get both at the same time, they can,” Fry says. In a Sept. 6 press briefing, White House COVID-19 Response Coordinator Dr. Ashish Jha concurred. “I really believe this is why God gave us two arms—one for the flu shot and the other one for the COVID shot,” he said.
Someday, it may be even easier to get dual protection against COVID-19 and the flu. Vaccine makers Moderna and Novavax are working on shots that would target both viruses in a single injection. It’s not clear if or when these combination shots might be available, but their development offers a glimpse into what living with both COVID-19 and influenza may look like moving forward.
Many unknowns remain about even this year’s looming flu season. Webb recommends keeping an eye on both COVID-19 and influenza rates and taking precautions accordingly. People at higher risk for severe respiratory disease, including elderly people and those with underlying conditions, might want to consider wearing a mask in crowded settings.
At least one thing makes Webb optimistic about this year’s flu season: Despite all the talk of pandemic fatigue, he thinks there’s been a cultural shift in the way people manage infectious diseases.
“People are, in general, much more aware now about the importance of infection control,” Webb says. “I would hope that we have a different culture in terms of recognizing that when you’re ill, it’s best to stay home.”
Write to Jamie Ducharme at jamie.ducharme@time.com.
