It’s fall north of the Equator.
Depending on where you live, that could mean more pumpkin spice, more leaf peeping, or more Oktoberfesting. But it also means flu season, and with the recent federal recommendation that a subset of Americans get a COVID-19 booster shot comes an interesting question: which vaccine should you get first—the flu or COVID-19?
The answer, says the US Centers for Disease Control and Prevention, is to whenever possible get them both at the same time.
The CDC is recommending boosters for a limited group of people who received their second shot of the Pfizer-BioNTech vaccine at least 6 months ago. That group includes anyone over the age of 65; people living in long-term care settings; people ages 50–64 with underlying health conditions; and people ages 18–49 with underlying health conditions or are at increased risk of infection based on their profession.
The CDC’s suggestion to get the shots in one visit is a practical one. The agency doesn’t want people to fall behind on routine vaccination schedules or from having to go to the doctor or pharmacy more than once. Last year in the US, nearly 52% of Americans got a flu shot, which was higher than normal—a level public health authorities would like to maintain. In addition, with hospitals all over the country overwhelmed by mostly unvaccinated people with COVID-19, keeping people with flu out of hospitals could help reduce the burden this season.
Researchers are still studying the safety and immunological profiles of receiving a COVID-19 vaccine alongside another vaccines, but the human immune system is pretty resilient, says Ian Barr, an influenza expert at the Peter Doherty Institute for Infection and Immunity, who also tracks the seasonal virus for the World Health Organization. He thinks that the CDC’s recommendation to get the shots at the same time is a good call.
“I wouldn’t expect there would be any, or very little interference with those two responses,” he says.
And for anyone getting a first or second COVID-19 vaccine, rather than a booster, adding on a flu shot at the same time is still OK, says Pedro Piedra, a physician who studies respiratory viruses at Baylor College of Medicine.
In Australia, which is emerging from a mild flu season, health authorities initially suggested waiting 14 days between any vaccines. That advice changed mid-season to a 7-day wait. In the end, the country had one of its lowest uptakes of flu vaccines in recent memory, Barr says, with just 33.5% of the population getting the vaccine. Typically, some 50–60% of Australians get the shot.
And Barr warns that the flu season might not be so mild in the US, where travel restrictions have eased and mask wearing, which keeps both SARS-CoV-2 and the flu from spreading, is spotty. Plus, the flu viruses that are represented in the vaccine have changed slightly in the months since it’s traveled through the Southern Hemisphere. The vaccine has been updated accordingly, he says, and there is no reason to pick one over the other.
“Any vaccine is better than no vaccine for influenza, or for COVID,” he says.