Skip to Main Content

For the health officials who steer vaccination campaigns, it’s going to be a complicated fall.

The U.S. plan to roll out updated Covid-19 boosters will not only coincide with the logistical tangle of the regular flu shot drive, but will also face questions about when people should get the new shots to provide themselves with the best protection through our third Covid winter.

It’s a balancing act that health officials run into every year with flu. Vaccinating tens of millions of people takes weeks. People also need a few weeks after their shot for their immune systems to be fully primed. And yet, vaccinators don’t want to put shots in arms too early, either. The power of the flu shot wanes over months, so the concern is that someone who gets a shot in say, September, may lose a chunk of their protection if the peak of the season is going to be in February.


The power of the Covid vaccines also wanes, with their ability to block infection fading over the months — though, crucially, the protection they generate against severe outcomes is maintained for much longer. But part of the reason the country is rolling out an updated shot is to better match the forms of the SARS-CoV-2 virus that are circulating now — to prevent more infections and to act as a drag on transmission during what could be another cold-season surge.

“When that comes out and we’ve got this extra coverage for the Omicron variants, that’ll be great,” said Sterling Ransone, a physician in Deltaville, Va., and the president of the American Academy of Family Physicians. “The question is the timing. I want my patients to have the best protection they can.”


Complicating the process is that scientists don’t have a sense yet — after only two winters with SARS-2 — about just when the virus might peak, and how strong the seasonal factors are. The virus has been spreading incredibly effectively throughout this summer, but many experts do anticipate even more elevated transmission at some point this fall and winter, at least in colder parts of the country.

Even with flu, it’s still a bit of a guessing game as to which month the virus will peak, particularly as Covid-mitigation efforts have thrown off the regular behavior of other viruses. And while the past two flu seasons have been tamed by the efforts to slow Covid, Australia is in the midst of a severe flu season, which can often portend what the U.S. season will look like.

“We’ve got a narrow window,” Patsy Stinchfield, a pediatric nurse practitioner and the president of the National Foundation for Infectious Diseases, said about the annual flu shots. “We want to make sure we’re not vaccinating too early, because then you risk a late season outbreak.”

Stinchfield said people should generally receive their flu shots by Halloween.

Ed Belongia, the director of the Center for Clinical Epidemiology and Population Health at the Marshfield Clinic Research Institute, said that flu vaccines lose about 8% of their effectiveness each month. But there is an important balance, too. While October might be a better time to get a flu shot than September, September is better than never — a lesson that should be applied to the Covid campaign as well.

“There’s a potential tradeoff between giving the vaccine too early versus missing opportunities to vaccinate people who then never get the vaccine at all,” Belongia said.

Running the two vaccine campaigns simultaneously could also stretch clinics and public health departments even further, though there is the advantage of people being able to get both their Covid booster and flu shot at one time if they choose to do so.

With annual flu shots, there is a well-choreographed system in place to have the shots ready by fall. Health officials typically pick which strains will go into that season’s shot early in the year, giving manufacturers months to mass produce the vaccine. From filling and shipping vials, to purchasing syringes, to getting health care workers and residents of long-term care facilities vaccinated, it is in itself a big lift every year.

With the updated Covid shots, it seems to be even more of a sprint. The Biden administration has signaled the boosters could be available in September, presuming the Food and Drug Administration and Centers for Disease Control and Prevention sign off on them. But it was only in late June that the FDA said the new boosters should target the original form of the virus as well as the spike protein of the BA.5 Omicron subvariant, the dominant lineage in the United States as of now.

“I used to think that flu was really challenging,” said Claire Hannan, the executive director of the Association of Immunization Managers. “There was never a year that was the same as the previous year. And I think the challenges around supply and trying to plan and optimal planning, they’re very difficult. And just when you think you’ve solved that, you haven’t. And throwing Covid boosters into the mix, it just makes it more complicated.”

Hannan said there wasn’t guidance yet from the federal government about how much of and when exactly the new Covid shots will be available. She also noted that public health departments are also fighting an unprecedented monkeypox outbreak, complete with a convoluted vaccine delivery process.

While the Biden administration hasn’t yet laid out its vision for the Covid booster campaign, it’s expected that it will be similar to when the original Covid boosters were authorized last fall, with more reliance on pharmacies and doctors’ offices and less on mass vaccination sites.

And in many ways, the sites are well practiced for another go-round with another Covid shot: they’ve dealt with different shots from different manufacturers, different booster doses, kids’ shots, and, already, extra boosters for older adults and people with certain health issues. One wrinkle, however, is that the updated shots are expected to be authorized only as boosters, whereas the primary series of shots will still use the original formulation.

Tinglong Dai, a health care operations expert at Johns Hopkins University, said that hospitals and clinics should be able to handle delivering the updated boosters. But he also pointed out that health officials need to embark on a crucial messaging campaign. Only about half those eligible for a first booster have received one, and people may wonder why they need an updated shot. It’s like someone with an iPhone 10 debating if they really need to upgrade to a newer model, Dai said.

Dai also said that the campaign needs to ensure easy access to both Covid and flu shots no matter where people live.

“The logistics aspects have been mostly resolved,” Dai said. “The challenge is now really to connect the supply and demand to access issues.”

With all the uncertainties around what the Covid winter might look like — when will the virus spike and just how high? what variant is going to be dominant? — Belongia said people shouldn’t try to time when they get their boosters to try to make sure their protection is maximized through whatever surge might come. Instead, people should just get the Covid shots when they can.

“Forecasting is a futile effort right now,” Belongia said. “If it’s available and authorized, the best thing is to not wait but to get it.”

Helen Branswell contributed reporting. 

Create a display name to comment

This name will appear with your comment