The Most Common COVID-19 Booster Shot Questions, Answered

Here's what the latest news on the additional doses means for you.

The Food and Drug Administration has authorized booster shots for certain recipients of the Moderna and Johnson & Johnson coronavirus vaccines — a decision that greatly expands the number of Americans eligible for boosters.

The FDA also now says it’s OK for people to mix or match COVID vaccines.

So, what does this latest guidance mean for fully vaccinated Americans and their loved ones? Here’s what you need to know:

1. When will the next round of COVID-19 shots roll out and who gets them?

The FDA said on Wednesday that certain people who received the Pfizer, Moderna, or Johnson & Johnson vaccines are now eligible for a booster dose.

Per the new FDA guidelines, you can now get a Pfizer or Moderna booster if it’s been at least six months since your second dose and you are:

  • 65 or older
  • 18-64 and you’re frequently exposed to COVID because of your job (so if you work in health care or education, for example) or live in an institutional setting

The Moderna booster dose is half the amount given for people’s first two shots. The Pfizer booster, which was authorized a month earlier, is the same dose as the initial two shots.

If you received the one-dose Johnson & Johnson vaccine, you are now eligible for a second booster dose if you’re over 18 and it has been at least two months since your first dose.

It is important to keep in mind, however, that the FDA isn’t the only regulatory group that will make a booster recommendation. The Centers for Disease Control and Prevention is expected to issue its guidance on Moderna and Johnson & Johnson boosters in the coming days. Once it does, boosters for those two vaccines could start rolling out quickly.

2. Why haven’t federal regulators recommended boosters for everyone?

The Biden administration initially said it wanted to give boosters to every American adult. But over the past several months, federal health officials have questioned whether mass boosters are actually helpful or necessary for all adults.

For now, they’ve decided to focus on groups at higher risk of severe disease and people who received the Johnson & Johnson vaccine, based on evidence showing a second dose makes it as effective against symptomatic COVID as the Moderna and Pfizer vaccines. To date, the majority of breakthrough COVID-19 cases in fully vaccinated individuals have been mild — and most hospitalizations around the country are people who are unvaccinated.

3. Can you mix manufacturers?

Yes, the FDA has approved a mix-and-match approach to boosters — though the CDC has not followed up with its official guidance yet. What that comes, there is likely to be specific, practical information available about how exactly boosters should be given (and what to avoid).

The FDA says that the timing of your booster dose should depend on what vaccine you got the first time around. If, for example, you got Johnson & Johnson, you could get a booster dose of any of the three vaccines two months after your initial dose. If you got Moderna or Pfizer, you could get a booster shot of any of the three COVID vaccines at least six months after your second shot.

4. What’s the difference between a ‘booster’ and a ‘third dose’? Are they the same?

Although the terms are often used interchangeably in discussions about Pfizer and Moderna shots ― the two mRNA vaccines ― booster doses and third doses are not exactly the same. Boosters are given to people who have already had a full course of the vaccine and developed a good response; third (or additional) doses are given to people who already had a full course of the vaccine and did not develop a sufficient immune response, like immunocompromised individuals.

That is why federal regulators approved a third dose for people who are seriously immune-compromised — meaning they’re undergoing cancer treatments, for example, or have HIV — more than a month before they approved Pfizer booster shots for people in other high-risk groups.

5. Will additional shots reduce breakthrough infections?

Yes. The decision to make another shot available to high-risk Americans is based on available data that makes it clear that protection against COVID-19 decreases over time.

Although breakthrough cases have been increasing, they remain quite rare. Also, the mRNA vaccines and the Johnson & Johnson shot continue to provide robust protection against the most serious outcomes like hospitalization and death, which is a primary goal of vaccination.

“The vaccine is still really protective against severe disease,” Adam Ratner, chief of the division of pediatric infectious diseases at Hassenfeld Children’s Hospital at NYU Langone Health, told HuffPost in August.

“Fully vaccinated folks, in general, are not the ones who are ending up in the hospital, ending up in the intensive care units,” he added. “The idea behind boosting is to make sure that we don’t get to that point.”

Health officials are now recommending COVID-19 booster shots for most Americans.
GoodLifeStudio via Getty Images
Health officials are now recommending COVID-19 booster shots for most Americans.

6. Why are these being recommended six or two months later?

Recommending boosters six months after the second dose of Moderna or Pfizer and two months after the Johnson & Johnson vaccine is really a best guess based on when immunity starts to wane.

And public health officials and vaccine manufacturers are continuing to learn about how long protection lasts. On Thursday, for example, Pfizer said a large study of people vaccinated with two doses of its shot showed full protection was restored after a booster.

In ongoing research, experts have been looking closely at antibody titers, which measure the levels of COVID-19 antibodies in the blood. But antibodies do not tell the full picture. The COVID vaccines prompt the body to produce T-cells, which are the main line of defense against the virus, experts say. They are also very difficult to measure, although recent studies suggest they’ve been unaffected by the COVID-19 variants, holding up even better than antibodies.

Ultimately, none of this means that your immunity suddenly falls off a cliff after two or six months. Participants in Pfizer’s new study, for example, got boosters an average of 11 months after their second dose.

“It’s not something where your immunity just turns off at some point. It’s a spectrum. You have optimum protection some time after that second dose — probably about a month after the second dose — and then you have a slow decay after that,” Ratner said.

7. What will the rollout be like?

Once the CDC weighs in, it should be pretty smooth.

Vaccine supply is not an issue in the United States, unlike much of the world. Also, because the shots are only being recommended for a subset of adults — and will be staggered based on when people received their second dose — there shouldn’t be a deluge of people wanting their follow-up shots all at once. Many adults who got the Pfizer vaccine initially have been eligible for a booster dose for nearly a month. Estimates suggest that 1 in 7 people 65 and older have already received their booster dose.

“It’s not going to be a crush of everyone trying to get a booster at the same time,” Ratner said.

8. What should you do if you lost your vaccine card?

It’s recommended that you keep your physical COVID-19 vaccination card in a safe place and that you take a picture of it so you have a record. Bring it with you when it’s your turn to get your next shot.

If you misplaced your card, though, don’t stress. Contact your original vaccine provider to see if they can verify your record or get you a replacement. You can also contact your state health department’s immunization information system.

9. What about kids?

Right now, kids ages 12 to 17 are not eligible for COVID boosters. And younger children are not even eligible for their initial doses, though that could change any day.

Ratner said he thinks it “wouldn’t be surprising” if eventually children do get a third booster, but we’re not there now. COVID cases in children have climbed because of the delta variant and because children make up a large share of the unvaccinated at this point, but severe illness and death remain rare.

10. Does everyone think boosters are a good idea?

No. From the get-go, boosters have been controversial from a global equity perspective, with the World Health Organization calling for a moratorium until more people around the world have received a first dose of a vaccine.

And experts say the most important step is making sure that everyone who is eligible for the vaccine gets it in the first place. Only about 57% of the U.S. population is fully vaccinated right now, and there are countries in the world where less than 1% of the population is fully vaccinated.

Still, if you’re eligible for a vaccine, doctors say there is no ethical reason to wait.

“You’re not skipping the line. You’re actually doing something that could help someone else,” Carl Lambert Jr., a Chicago-based family physician, previously told HuffPost. “You’re reducing harm to your neighbor if you follow these guidelines.”

This article has been updated to include new information available about COVID booster shots.

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.