The Most Common COVID-19 Booster Shot Questions Answered

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

Federal health officials have greatly expanded the number of Americans eligible for booster shots, approving Pfizer and Moderna booster doses for anyone 18 and older. And people 18 and up who received the Johnson & Johnson vaccine have already been eligible for a booster dose — which basically means most fully vaccinated adults qualify for an additional dose at this point.

So do you have questions about why boosters are being recommended and what the process is like? Here’s what you need to know:

1. Is anyone NOT eligible for boosters now?

If you’re 18 or older and you’re fully vaccinated, you’re eligible to be boosted if it’s been at least six months since your second dose of an mRNA vaccine or two months since you received the Johnson & Johnson shot.

This week, the FDA and the Centers for Disease Control and Prevention OK’d booster doses of the Pfizer and Moderna vaccines for anyone 18 and older after that six-month stretch. Previously, only people who were older than 65, who had certain underlying health conditions or who lived or worked in high-risk settings qualified.

The booster for the one-dose Johnson & Johnson vaccine had already been approved for those 18 and older, as long as it had been a two-month stretch.

2. Should you mix manufacturers?

Federal health officials have said it’s OK to mix-and-match vaccines, and it’s pretty widely recommended at this point. Most experts say getting boosted with one of the two mRNA vaccines is really your best bet regardless of what you got when you initially you rolled up your sleeves.

The mRNA vaccine you go for doesn’t seem to matter much. It’s not clear whether there are any benefits to getting boosted with Moderna if you initially had the Pfizer shots, or vice versa. Right now, it really comes down to personal preference and availability — though doctors and researchers are learning about boosting in real-time.

That said, you’ll still get benefits from getting another dose of the Johnson & Johnson vaccine if that’s what you went with the first time around. According to the company, a booster dose of its vaccine provides 94% protection against moderate to severe COVID — and can increase initial antibody levels by four to six times.

3. 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 — well before they approved booster shots for people in other high-risk groups.

4. Will additional shots reduce breakthrough infections?

Yes. The decision to make another shot available to Americans is based on available data that makes it clear that protection against COVID-19 decreases over time. It’s not clear how common breakthrough infections are at this point because federal health officials really only track cases that end in hospitalization or death, which remains rare. But breakthrough cases can and do happen, so the goal with boosting is both to prevent them and to help make sure that when they do happen, the outcome is relatively mild.

“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, previously told HuffPost.

“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.

5. 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. 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.

“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.

6. What will the rollout be like?

There’s no reason to believe it won’t be pretty smooth.

Vaccine supply is not an issue in the United States right now, unlike much of the world. Also, 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 months.

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

7. 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.

8. What about kids?

Right now, kids ages 12 to 17 are not eligible for COVID boosters. And kids ages 5 to 11 only just became eligible for their first shots, so it’s really a non-issue for them right now.

Ratner said he thinks it “wouldn’t be surprising” if eventually children do get a third booster, but not yet. 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.

9. Does everyone think boosters are a good idea?

Boosters have been controversial from a global equity perspective, and the World Health Organization had previously called for a moratorium until more people around the world have received a first dose of a vaccine. The group has since softened its stance somewhat, saying that the evidence to date on the need for boosters is “inconclusive” and that giving out boosters risks increasing vaccine inequity around the world — but stopping short of calling for a booster ban.

It’s certainly true that experts say the most important step is making sure that everyone who is eligible for the vaccine gets it in the first place. Fifty-nine percent of the total U.S. population has now been fully vaccinated. Globally, only 53.8% of people have received at least one dose.

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.