To boost or not to boost: 10 questions about Covid-19 boosters answered

There's a lot of conflicting information about Covid-19 booster shots. Here's what you need to know.

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I can’t decide if I should be mad about not qualifying for a Covid-19 booster shot. I got both doses of the Pfizer vaccine, and I feel reasonably confident that, were I to contract a breakthrough infection, it wouldn’t hospitalize or kill me.

But I still don’t want Covid-19. I have less risk of developing Long Covid from a breakthrough infection than someone who’s unvaccinated, but the risk is not zero. I’m also young, healthy-ish, and an obnoxious rule follower when it comes to public health. But I also don’t know how badly I should want a booster or if I need one.

If my internal debate feels familiar to you, know we aren’t alone. Heated debates online about vaccines fuel the confusion over booster shots for Covid-19, but public-health institutions like the WHO and the CDC giving out conflicting information doesn’t bring clarity, either.

So should you get another shot or not? Inverse asked Donald J. Alcendor, an associate professor of microbiology and immunology in the Center for AIDS Health Disparities Research at Meharry Medical College, and William Schaffner, an infectious disease specialist at the Vanderbilt University Medical Center, for answers to the most pressing questions we have about boosters. Here are the answers to our 10 biggest questions.

10. When will Covid boosters be available?

The Pfizer-BioNTech Covid-19 vaccine booster shot is available to some Americans now. But whether you are eligible for a Covid-19 booster depends on a few conditions.

First, only people who have had two doses of the Pfizer-BioNTech Covid-19 vaccine at least six months ago can qualify for a booster shot at the time of writing. If you got the Moderna or Johnson and Johnson coronavirus vaccine, know that emergency approval for those boosters is likely right around the corner (more on that below).

9. Who qualifies for a Covid booster shot?

If you are six months out from your last dose of the Pfizer-BioNTech vaccine, you’re eligible for a booster only if you also meet one (or more) of the following criteria:

Sounds pretty straightforward, right? Not so simple, Schaffner says.

“Depending on your work or living circumstances, those categories are remarkably nebulous,” he says.

Schaffner is a “liaison representative” of the CDC’s Advisory Committee on Immunization Practices, which means he attends the meetings and participates in the discussions around vaccines, including the coronavirus vaccines. Still, he does not get a say on final decisions.

That said, the CDC lists what it considers to be high-risk occupations and living environments on its website.

Dr. Richard Schwartz celebrates after receiving a Covid-19 Pfizer-BioNTech vaccine booster at Teaching Center LIJ Medical Center.

Getty/Pacific Press

8. Should I get a booster if I have an underlying medical condition?

Some of the underlying conditions that qualify you for a booster are perhaps what you might expect, given what we now know about the virus. They include:

  • Autoimmune diseases
  • Diabetes
  • Heart conditions
  • Cancer
  • Obesity

Other qualifying conditions are less obvious — even subjective. For example, “smoking, current or former” is on the CDC list of qualifying underlying conditions for a booster shot.

What exactly does that mean? If you smoke a couple of cigarettes at a college party, does that count as “smoking, current?” What about if you were a heavy smoker and then quit 20 years ago?

Alcendor says there’s an excellent reason for ex-smokers to get a booster shot, especially if they were once a heavy user — because Covid-19 is a potentially fatal respiratory virus, and smoking damages the respiratory system.

“If you think about being a smoker 20 years ago, the lungs don’t forget that. It could predispose you to chronic conditions that are life-threatening,” he says. “What happens to your pulmonary system might not reveal itself until 20 years later.”

Also, the people giving out the booster are unlikely to ask you for proof of anything, Alcendor and Schaffner say. They’re going on the honor system. They will ask to see your vaccination card to make sure you’re six months out from your last dose of Pfizer-BioNTech, but beyond that, it’s up to you to be as honest about your situation as you can be.

7. Are Johnson & Johnson and Moderna’s Covid-19 vaccines approved for booster shots?

Schaffner expects a Moderna vaccine booster shot to be approved sometime in mid-October, and the Johnson & Johnson vaccine booster shot will be approved not long after that.

6. Will the qualifications for a booster change?

The short answer is yes, says Schaffner.

Schaffner says in the most recent CDC meeting he attended as a liaison representative to the advisory committee, “it was stated more than once in the meeting that this is a work in progress and will be updated.”

But the timeline for any changes is not public knowledge at this time.

5. Is the Covid-19 booster the same vaccine as the first two shots?

Pfizer-BioNTech’s emergency-approved booster is the same vaccine formulation and dose as the first two. It’s just a third round of the two shots you got before.

The booster Moderna has submitted for approval is also the same formulation as its initial vaccine, but the dose is smaller.

Both Pfizer-BioNTech and Moderna are working on Delta-specific boosters. Still, research suggests that the antibody benefits one gets from a booster made using the original vaccine formulation should offer sufficient protection against Delta, too.

The proposed booster for the Johnson & Johnson vaccine also has the same formulation as the original vaccine.

4. How do I balance the CDC advice to get a booster and the WHO advice not to?

Alcendor says people living in the U.S. should follow the CDC guidelines.

“The WHO looks at this on a much broader scale and may see things differently,” Alcendor says. “But people in the United States should look to the CDC and FDA for guidance.”

“The CDC is sanctioned to protect the health and wellness of people in the United States,” he adds. “And the CDC [consults with] a number of different bodies before they make a decision.”

The FDA, various vaccines boards, public health experts, and the scientific community all discuss the data on the Covid-19 vaccines. These data are collected in the United States and around the world. The evidence as a whole is all taken into consideration when the CDC develops its guidelines (and might explain why the policies are not always simple or straightforward).

3. Why do we need Covid-19 booster shots? Will my vaccine wear off?

The timeframe for waning immunity depends on the age and health of the vaccinated person.

“Think of a vaccinated immune system as car tires full of air,” Alcendor says. “Over time and very slowly, the air in those tires decreases. What a booster does is fill the air back up.”

Some people lose air in their tires more quickly than others. In this analogy, immunocompromised people typically lose their “air” faster than younger people with more robust immune systems.

“A young, healthy person doesn’t really need a booster right now, in the minds of scientists, the FDA, CDC, and so forth,” Alcendor says.

“Studies suggest that their existing immune effectiveness against [the virus] is enough to keep them from being severely ill and preventing them from being hospitalized and dying of Covid. And that includes the Delta variant.”

Over time, antibody protection does wane, but it’s just hard to say how quickly that occurs in younger, healthier people. Alcendor says it’s likely the recommendation will eventually be for everyone who has had their initial vaccination to get a booster.

More importantly, Alcendor stresses, is getting as many unvaccinated people a Covid-19 vaccine as fast as possible — and getting boosters to the most vulnerable vaccinated populations.

Even if you’ve gotten a Covid-19 booster, masks will likely still be required indoors until more people are vaccinated.


2. If I get a booster shot, can I stop wearing a mask?

“Not yet,” says Schaffner. “I know that will make people unhappy. But it’s because Delta is contagious. Once new infections in the communities go down, then we might be able to take them off.

“Though I would still be cautious if you’re older, immunocompromised, or in another high-risk group.”

People who spend time around unvaccinated groups, like young kids, may also need to keep wearing masks until everyone they’re regularly in contact with is vaccinated.

Alcendor warns that we might see mask guidelines on and off as community transmission increases and decreases — especially as immunity among the vaccinated wanes.

But once enough people in the community are fully vaccinated and community transmission decreases, mask requirements will become less necessary.

1. What is the Covid booster shot, and what level of protection does it give you?

The level of protection a Covid-19 booster confers on a person is a very compelling reason to get a booster as soon as you’re eligible. Schaffner says the protection a person receives from the booster will increase your antibody levels beyond the point where they were after your initial vaccination.

“That will give you two advantages,” he explains. “One is likely longer duration of protection. And the second is that we have laboratory evidence to suggest that you get better protection against the variants.

In other words, not only will you have longer-lasting protection from the initial variants of the coronavirus, but you will likely also have increased protection from Delta and other emerging variants. There’s no telling what variants are in our future, but it’s a safe bet that getting a booster will give you more protection against them than if you skipped the third shot.

It might feel like you have lived millennia with Covid-19 on the rise, but it is a little under two years in reality. That’s a relatively short time for a virus. And we’ve only had available vaccines for less than a year of that time. This short period means we have a lot to learn about the virus — and that means there will be changing information and shifting guidelines.

What’s clear is that everyone should get vaccinated for Covid-19; six months after that, people in vulnerable groups should get booster vaccines. If you want to get a booster but don’t quite fit the criteria yet, hang tight. When vaccines first started to roll out, some people had to wait before they became eligible. The chances are it could happen this way for booster shots, and you will be eligible in the not too distant future.

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