Do I Really Need the COVID Booster Shot?

A third shot for the coronavirus has been all over the news lately. What’s the deal?

by Erin L. Boyle Health Writer

Say you’ve had your two mRNA COVID-19 vaccines, or your single Johnson & Johnson shot here in the U.S. Now you’re hearing about new COVID variants, like Delta, that seem concerning—so your next question is, will my current vaccine(s) be enough to protect me from this variant and future iterations of the coronavirus? Followed by, if not, does that mean I need a booster shot now?

Officials at Pfizer-BioNTech, which makes one of two available mRNA COVID-19 vaccines (the other is from Moderna), appear to think so. They made news in mid-July 2021 when they announced that their shot, found to be 95% effective at preventing COVID-19 when fully vaxxed, declined in efficacy six months post-vaccination for both preventing infection and symptomatic disease (but remained strong at preventing serious illness). They based this on “real world data” from the Israel Ministry of Health in Israel—where the Delta variant (which the vaccines have shown good efficacy against) is becoming the dominant strain.

They’re conducting an ongoing booster trial of a third dose, reporting that initial data found this extra dose given six months after the second vaccine dose improves protection against virus variants five to 10 times more than the two primary doses alone. (Specifically, the booster causes the amount of antibodies to COVID in a person’s blood to increase, and Pfizer-BioNTech believes waning antibodies are causing their vaccine to be less effective over time.)

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The FDA and CDC Statement on COVID-19 Boosters

But then the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention issued a joint statement contradicting the pharmaceutical companies’ vaccine venture, stating, unequivocally, that a booster shot was not necessary. “People who are fully vaccinated are protected from severe disease and death, including from the variants currently circulating in the country such as Delta,” the statement concluded.

So… which is it?

We asked Jason Gallagher, PharmD, a clinical professor at Temple University School of Pharmacy and clinical pharmacy specialist in infectious diseases at Temple University Hospital in Philadelphia, to give us the bottom line.

HealthCentral: Why would someone need a booster shot for COVID-19?

Jason Gallagher, PharmD: There are three reasons why one may need an additional dose of vaccine after already being fully vaccinated. The first reason is a classic booster shot, which is given to prevent a declining immune response from being insufficient to prevent infection. An example would be tetanus, which require boosters every 10 years. The second is to give someone immunity to different variants or types of the original pathogen. This is similar to what is done with influenza, since the strains of the virus change every year.

The third reason is that someone may not develop a sufficient level of protection from the normal dosing regimen. Sometimes we give one or more doses of vaccine to “boost” them to a level that protects. Hepatitis B vaccine is a good example of this.

With COVID-19, we don’t have enough experience to know if additional doses will be required for any of these reasons, and people are getting nervous. So far, the immunity from the vaccines seems to be pretty durable, so there is no reason for the classic boosting dose yet. But it is likely that some people, primarily who are immunosuppressed, will not have a sufficient response after two doses. I am most interested in them for boosters.

HC: So what’s the bottom line? Do we need a COVID booster or not?

Gallagher: The bottom line is the easiest part—no, we don’t.

HC: Why is Pfizer applying for FDA approval for a booster shot if their vaccine is 95% effective?

Gallagher: In the one sense, it is a bit quizzical. Personally, I think they are jumping the gun by talking about the need for a booster. I think it makes sense to be prepared and study how well boosters increase immune response and if doing so is safe. So studying it is smart, and National Institutes of Health is also studying this with other vaccines. But I think that whether it is safe and effective or not, it very well may not be necessary. We don’t know if that is the case or not.

HC: Is it typical to need a booster shot so soon after being vaccinated?

Gallagher: We have never had the ability to employ vaccines like this in a way that can shape the trajectory of a pandemic. These are really uncharted waters. The reason we may need additional doses early is because the pandemic is uncontrolled, and as long as there are many infections going on, there are chances for the virus to change in a way that makes vaccines less effective. The more vaccinating we do, the more quickly the pandemic is controlled and the less likely that continued doses are needed.

HC: How would a booster shot be different than the vaccine itself?

Gallagher: It would be one of two things, depending on the reason for the booster. If waning immunity is the reason, then the booster shot would be the same as the vaccines currently being used. It’s likely that people could receive either the same vaccine or a different one. This is something being studied now. If new variants are the reason, then the vaccine “recipe” would be slightly different to teach the body how to defend against a new variant. This is one area where the new types of vaccines we have are really wonderful, because they can be changed easily and very little of the vaccine itself would change. It would be like adding a new chapter of a book that the immune system has already read.

HC: Would a booster shot target the Delta variant or other variations?

Gallagher: It depends again on the reason. So far, we don’t think most people need boosters for any reason. If a variant emerges that the vaccines are less effective against, then a booster might be necessary.

I think an important message is that the vaccines available to us so far aren’t home runs, they are grand slams. I never thought we would have a vaccine available that is so effective so quickly, let alone multiple vaccines. They are a huge success.

Erin L. Boyle
Meet Our Writer
Erin L. Boyle

Erin L. Boyle, the senior editor at HealthCentral from 2016-2018, is an award-winning freelance medical writer and editor with more than 15 years’ experience. She’s traveled the world for a decade to bring the latest in medical research to doctors. Health writing is also personal for her: she has several autoimmune diseases and migraines with aura, which she writes about for HealthCentral. Learn more about her at Follow her on Twitter @ErinLBoyle.