Everything You Need To Know About COVID-19 Boosters Right Now

Will we need coronavirus vaccinations every year? How will variants affect immunity and new shots? Here's the latest.
Experts increasingly believe COVID-19 booster shots will be necessary — but when is not yet clear.
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Experts increasingly believe COVID-19 booster shots will be necessary — but when is not yet clear.

The COVID-19 pandemic has swerved yet again in recent weeks. The highly-contagious delta variant is spreading — overwhelmingly among the unvaccinated — and new reports have emerged suggesting even the fully vaccinated may be affected by it.

But there’s still plenty of good news. The Pfizer, Moderna and Johnson & Johnson COVID-19 vaccines continue to work — and not just against the initial strain of the virus. And they’re keeping fully vaccinated people who happen to get breakthrough infections from getting really sick or dying.

But what the next few months hold, and whether we are truly inching toward a return to long-term normalcy, is not yet clear. And one possible determining factor is whether Americans are going to have to roll up their sleeves for another COVID-19 shot — or shots — and when.

Will we need to get one regularly, like a flu shot? What will the rollout process for boosters look like in the next year? Here’s what we know so far:

We don’t know how long immunity lasts — and that determines when we need COVID-19 vaccine boosters.

Many experts now believe that immunity against COVID-19 is going to wane with time, but no one really knows when. Nor do researchers know exactly how much a person’s immune response has to dip in order for the vaccines to stop doing their job. So far, research shows the Pfizer and Moderna vaccines offer robust immunity for at least six months, but what happens beyond then isn’t clear yet.

“We’ve had to very openly say from the get-go that we do not know what the durability of the mRNA vaccines or the J&J vaccines are,” Cameron Wolfe, an associate professor of medicine specializing in infectious diseases with Duke University’s School of Medicine, told HuffPost in May. “We knew great safety data. We knew great efficacy data. We did not know great durability data, because they haven’t been around for that long.”

Experts can try and answer that question in a few ways. The first is to use models to try and formulate a best guess.

“You can project how long it’s going to last by seeing a number of different time points and seeing how much antibody levels — or T-cell function, how good your immune system is at its broadest capacity — how long that lasts,” Wolfe said. “So if I know what it is at baseline ― if I know what it is after you’ve finished the vaccine course, and I know what it is at, say, three and six months ― then I can see how much decline may have taken place and extrapolate that.”

Then there is also real-time data collection. Wolfe, who was a volunteer in the early Phase 3 clinical trials for the Pfizer shot, and others like him continue to enter their results each week, saying whether they’ve developed COVID-19 or not.

“We can then model against those who took a placebo how long it’s expected to last for,” Wolfe explained. “That’s real, hard case data.”

Some experts believe boosters will be necessary soon, but not everybody agrees with that assessment.

If immunity does wane over time, then subsequent COVID-19 shots will be necessary. Moderna recently indicated that a third dose will be necessary to “keep us as safe as possible” through the coming winter. Pfizer has also indicated that a third dose may boost protection against the delta variant. Some countries even announced they will offer a booster to certain high-risk populations.

However, the WHO recently called for a three-month moratorium on boosters, urging health officials to focus instead on vaccinating people around the world. And the Centers for Disease Control and Prevention has indicated that boosters are not necessary now, and that it is working with other public health organizations to determine if and when they might be needed down the road. To date, research shows that the vaccines hold up well against the variants, even delta. A July study found, for example, that two shots of the Pfizer vaccine were 88% effective at preventing symptomatic infection from the delta variant.

Wolfe said in May he’d “be very surprised if it was in 2021. Beyond that, I’d be surprised if it wasn’t in 2022.”

Variants are a significant factor in all of this.

Emerging variants and their impact on efficacy may just be what determines if subsequent COVID-19 shots are necessary, Wolfe said. That’s because if variants emerge that are able to dodge our current vaccines, people may need a reformulated shot that does a better job of targeting them.

Moderna, for example, has been taking a close look at how a booster developed specifically to fight against the COVID-19 variant found in South Africa works against that strain. Pfizer and Johnson & Johnson are also conducting various booster trials, including research looking specifically at how boosters might work against the delta variant.

The companies are also investigating whether a booster shot of the same formula will do the trick, or if their current vaccines need to be tweaked to better take on the variants. Additionally, the National Institute of Allergy and Infectious Diseases is planning studies to look at what happens if people mix-and-match vaccines — if boosters are, indeed, necessary. For example: Would it be possible for someone who received the Johnson & Johnson shot initially to get a Moderna booster?

And those are just some of the questions that linger about COVID-19 variants what they mean for our collective immunization efforts — and for the pandemic as a whole.

“We know increasingly reassuring information about durability, but the variant question remains open,” Wolfe said.

All of which points to the pressing need to get as many people around the world vaccinated as soon as possible in order to stop the virus from spreading and evolving as it does.

The vaccine manufacturers also play a role.

“Pharmaceutical logistics and how they need to study a new booster, how they need to go into production and whether it’s efficient for them to try and combine those with alternative vaccines” will all play a role in the timing of potential COVID-19 boosters, Wolfe said.

“Those are company decisions as much as they are medical ones, but they factor in,” he added.

If a subsequent shot (or shots) are necessary, the process should hopefully be smoother than the initial vaccine rollout was. Some scientists have argued that any adjusted vaccines should not have to go through the same level of scrutiny that the initial vaccines were subject to, in much the same way that a new flu vaccine is updated annually without a long approval process.

But while planning and thinking ahead is important, experts say it is even more critical to focus on the here and now, particularly as variants like delta circulate and new variants arise in people who are unvaccinated.

“Frankly,” Wolfe said, “we need to understand how to better vaccinate our current population.”

Experts are still learning about COVID-19. The information in this story is what was known or available as of publication, but guidance can change as scientists discover more about the virus. Please check the Centers for Disease Control and Prevention for the most updated recommendations.