A patient discusses a booster shot with her doctor.

Your Questions About Booster Shots, Answered

September 29, 2021
David Buchholz
David Buchholz

The U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) have authorized COVID-19 booster shots for certain populations who received the Pfizer COVID-19 vaccine. Based on all available data, certain groups who can benefit from additional protection are now eligible for a booster dose. But does everybody need one?

We spoke with David Buchholz, MD, senior founding medical director for primary care at ColumbiaDoctors, for answers to frequent questions about booster shots. We discussed immunity, vaccine hesitancy, when to get your booster dose, and more.

Why are booster shots now being made available to some people?

The delta variant of the SARS-CoV-2 virus is the dominant strain causing COVID-19 infections in the United States. It’s more contagious than previous strains, and a booster shot will help strengthen protection against severe disease in the populations at highest risk of exposure to COVID-19 or the complications associated with severe disease.

Who should get a booster shot?

After the FDA and CDC made their recommendations, the final decision opened boosters for people who are 65 and older, people 50-64 years old with underlying health conditions that put them at high risk of complications from COVID, and adults in long-term care facilities. They’re the same populations we were most worried about when vaccines first arrived—the people we wanted to be first in line for a vaccine. Those groups should receive a booster dose if they have previously received two shots of the Pfizer vaccine and it’s been at least six months since their second Pfizer shot. 

The other groups that are now eligible are 18- to 49-year-olds who might be in that high-risk category because of underlying health conditions and adults with occupational risks, such as health care workers, teachers, and grocery store workers. Those people should also talk to their doctor, and on a case by case basis, their doctor might recommend a booster shot.

A patient receives a booster shot.
Why a booster shot, and why now? The COVID delta variant is a primary concern. "It’s more contagious than previous strains, and a booster shot will help strengthen protection against severe disease in the populations at highest risk of exposure to COVID-19 or the complications associated with severe disease," Buchholz says. Photo: Courtesy of CDC

Will everybody—even people not included in these groups—eventually need a booster shot?

Part of the difficulty around the booster conversation is that we see that most vaccinated people are still protected against serious illness even after six months since their second vaccine. There's not enough data to support booster shots for the entire population, at least not right now. That may be part of the reason there's been a lot of misinformation or misunderstanding around booster shots. A booster shot may prove to be beneficial for them once we have more data. But at this time, only those approved groups are eligible.

But we do have data to suggest boosters can be beneficial to the groups mentioned above, and we have plenty of vaccines in the United States, so it makes sense for particular populations to go ahead and get a booster when it's time.

What if I received the Moderna or Johnson & Johnson vaccine? Should I get a booster dose?

Not at this time. The data on boosters for those vaccines are not in yet. In an ideal world, we would know if everybody needs a booster shot and if that were the case, we would be telling people to go in and get a booster shot regardless of which vaccine they had. But it's not an ideal world, and we need to see more data before we can make that recommendation. So for now, we're asking people who have had Moderna or Johnson & Johnson shots to be patient. Hopefully in the next few weeks we will have clear indications for who else should have a booster shot.

What’s the difference between a booster dose and an additional dose?

People who were immunocompromised when they had their first set of shots never got quite the level of immunity we would hope for, and so we have been recommending for a long time now that they get a third shot. We don't call that a booster; that’s an additional dose. We're trying to keep that language separate and that population separate.

So if you were immunocompromised during the time that you got your first shots, you really should get a third shot regardless of the interval. As long as it's been a month or more since your second shot, you should get a third shot. People who are in these other categories need a booster if it's been six months since their last dose.

A patient discusses a booster shot with her doctor.
Patients who received the Moderna or Johnson & Johnson vaccines will need to wait for approval on booster doses. "The data on boosters for those vaccines are not in yet," Buchholz says. "Hopefully in the next few weeks we will have clear indications for who else should have a booster shot." Photo: Courtesy of CDC

Why should I get vaccinated if the vaccine already needs a booster shot to protect me? Are vaccines not effective?

We know that the vaccine is not perfect; people do get breakthrough infections. But understand that the vaccine is as much about preventing serious disease—that means preventing hospitalization and death—as it is about preventing infection. Our goal with these vaccines is to prevent those more serious cases. And the vaccines are very, very effective in that regard.

But unfortunately, there are still a lot of Americans who are hesitant to get the vaccine. They are part of the reason that hospitals are clogged in some states and part of the reason that lots of people are still dying. And now there is some evidence to suggest that even talking about boosters is increasing their hesitancy to get vaccinated. They are asking, “Why should I get the vaccine if I have to get boosted?” Truthfully, there’s not much logic behind that concern, but we need to meet them where they are, because we need everyone to get vaccinated.

Once in a while, you get a celebrity—an actor, an athlete, somebody with a public persona—who will say, “I've been fully vaccinated and I got COVID anyway, and it was serious! I was sick, I was in bed!” And that influences people’s perception of the vaccine and its effectiveness. Yes, there will still be vaccinated people who get sick and need to stay home, drink fluids, and get rest. But they aren't often hospitalized. They don’t often die. That’s the vaccine working. It’s frustrating, because serious COVID cases are still incredibly rare in vaccinated people, but they get a lot of press.

Are three-shot vaccines very common?

Absolutely. And that's why resistance or criticism of a booster doesn’t make sense to a clinician. I'm a general pediatrician, and we give the same shots at 2, 4, and 6 months of age. And then we boost them somewhere between 12 and 18 months of age, we boost them again at age 4, and then we boost them again at 12. This whole concept of boosting immunity against high-risk diseases is well established.

We're constantly boosting. We get boosters for measles, mumps, and rubella before we go to college. We give a booster shot for tetanus, diphtheria, and pertussis (Tdap) to every woman who's pregnant—every time they're pregnant—because we're trying to boost their immunity against pertussis, which is also called whooping cough, so that they're not getting whooping cough and giving it to their baby. We boost all the time.

Should we expect more COVID-19 booster shots to follow, like an annual flu shot?

The most common boosters that people think of, of course, are flu boosters. There are changes in the shot most years to adapt to the variant of flu, because flu is constantly creating variants. And so we change the flu shot to a variant booster and we get boosted again. That’s just like if we were to get a fourth booster shot for COVID. Someday, the COVID vaccines probably will be tweaked to adjust to a variant, just like a flu shot is, and that is normal. It's expected. We will continue to boost for as long as the disease is in the community.

If the disease goes away, we'll stop giving COVID shots and we won't need boosters. Smallpox is a perfect example: We gave smallpox shots for decades, but we don't do smallpox shots at all anymore because we eradicated it from the population due in large part to the vaccine.

man receiving COVID vaccination while sitting in his car
Concerned about the timing of your COVID booster shot and other vaccinations, like the flu shot? There's no harm in getting the booster alongside other vaccinations, Buchholz says. "Side effects are also not additive or worse if you get multiple shots together," he adds. "I got my Pfizer booster and flu shot on the same day at the same time." Photo: Getty Images

Is the timing of my booster shot important, relative to other vaccines? Can I get it at the same time as my flu shot, or along with another vaccination, like shingles?

There’s no harm in having them at the same time. When the COVID-19 vaccines first came out, we recommended not getting the vaccine within two weeks of another shot. We needed data to confirm that your immune response to the COVID-19 vaccines wasn’t reduced by getting another shot at the same time. Once we had data that confirmed a COVID-19 shot with another shot on the same day or within two weeks of each other didn’t affect your immune response, we dropped the recommendation.

Side effects are also not additive or worse if you get multiple shots together. Using my pediatric example again, at 2 months of age, we immunize infants against eight different diseases with minimal or no side effects. And it’s convenient to get shots together so you don’t have to schedule multiple visits. I got my Pfizer booster and flu shot on the same day at the same time.

Are people more likely to have fever, aches, etc. (or “vaccine reactogenicity”) after a third dose? How should I prepare for my booster shot?

For Pfizer in particular, a lot of people didn't have issues with the first shot other than some pain around the injection site. It was really the second shot that produced more symptoms, like fever and fatigue. Those usually show up around 12 hours after the shot and disappear by 36 hours for the vast majority of people. People who've been getting a third shot because they are immunocompromised have been getting a little bit of that, and I expect people getting booster shots may experience it as well. So it’s best to assume you're going to get some of that.

If those symptoms would potentially disrupt your ability to work, you might want to get the shot the day before a day off, just so that you don't have that issue at work. Be prepared, but know that you may not even get those symptoms, and if you do, it’s really no big deal. You can take some acetaminophen or ibuprofen to help make you feel better.

When might we see the booster shots approved for the entire adult population?

I think there will come a time when we see increasing evidence of serious infections even in average-risk people who got their second shot more than six months prior, people at a relatively young age. At that time, we’ll know that we need to begin boosting that population.

But we don’t have a good idea right now of when that will be. I think as we gather data and we get a better understanding of how long the immunity lasts for all different age groups, we will start to recommend a general booster for everybody.

Closing thoughts?

Booster shots are an important story and an important tool for us to protect the most vulnerable. But the more important story is that if you haven't been vaccinated, we are asking you to please get vaccinated. Booster shots are important, but getting everybody vaccinated is even more important.


Schedule Your Booster Shot

Eligible ColumbiaDoctors patients can make a booster shot appointment through their Connect account.

Vaccines are also available at local pharmacies and drug stores. The following websites can help you find a vaccination location:

Be sure to check for a location that has the Pfizer vaccine available. Visit the CDC website for more information about booster shots and underlying medical conditions.