Need a Boost? URMC Experts Answer Your Questions About COVID Vaccine Boosters

Jul. 14, 2021


January 5, 2022: Thanks to recent decisions from the U.S. Food and Drug Administration and Centers for Disease Control and Prevention, everyone over the age of 12 is now eligible for COVID vaccine boosters.

Learn more about COVID boosters from our experts.

Pfizer and BioNTech announced plans last week to seek emergency use authorization for a COVID vaccine booster shot, and to start clinical trials in August on a new COVID vaccine targeting the Delta variant. Almost immediately, the Centers for Disease Control and Prevention and the Food and Drug Administration put out a joint statement reassuring Americans that they do not need COVID booster shots at this time.

All of that has left us wondering if and when we’ll need a COVID vaccine booster. The University of Rochester Medical Center put those questions to three of our COVID vaccine experts:


Angela Branche, M.D.

Assistant professor of Infectious Diseases and co-director of the University of Rochester Vaccine and Treatment Evaluation Unit


Ann Regina Falsey, M.D.

Professor of Infectious Diseases and co-director of the University of Rochester Vaccine and Treatment Evaluation Unit


Edward Walsh, M.D.

Professor of Infectious Diseases at URMC and head of Infectious Diseases at Rochester General Hospital.

Do I need a COVID vaccine booster?

Walsh: No, vaccinated people do not need boosters right now. At my hospital, we have seen only one person that was immunized who later needed to be hospitalized for COVID. Nationally, 99.5% of all people who are hospitalized with COVID are unvaccinated, which shows the vaccines are still very effective even with the variant viruses circulating.

If not now, will I need a COVID vaccine booster in the future? When?

Falsey: We don’t have enough data to know exactly when, but COVID booster shots will likely be needed at some point. The original vaccine studies will follow participants for two years to see if and when breakthrough infections occur in vaccinated individuals. Those breakthrough infections – and their severity – are our best indication that a vaccine’s effects are wearing off. In normal circumstances, we might not worry about boosters if the breakthrough infections are mild. But when you’re trying to control a pandemic, we might recommend a booster to try to shut down as much mild disease as we can to prevent spread.

Would the booster be a new vaccine or a third dose of the one I already got?

Falsey: It could be either. Studies are ongoing to see if we need to change up the vaccine to better target new variants, like Beta (South African) or Delta, or if a third dose of the same thing can boost your antibody levels and protect you just as well. We’re also studying if you can mix and match COVID vaccines and boosters from different manufacturers. For example, if you got the first two shots of the Pfizer vaccine, will a booster from Moderna work for you?

Is the Delta variant here?

Walsh: Yes, the delta variant now accounts for over 50 percent of COVID cases in the U.S. – making it the most prevalent variant nationwide. We have also seen it locally, but it represents a small percentage of local cases.

[Editors’ note: Dwight Hardy, Ph.D., director of clinical microbiology for UR Medicine Labs, provided this detail: “We continue to monitor for the presence of the Delta variant in our community. Nineteen percent (19%) of 54 PCR-positive specimens collected from area patients during the period of June 2, 2021, thru June 16, 2021, and tested in UR Medicine Labs were positive for the Delta variant as determined by Whole Genome Sequencing.”]

Can I catch COVID from the Delta variant even if I’m vaccinated?

Branche: Luckily, current vaccines do appear to be effective against the delta variant. Most, if not all, people infected with this variant in the U.S. have been unvaccinated. The Delta variant is just another reminder that this pandemic is not over. If you haven’t been vaccinated yet, it’s not too late.

So, is Pfizer jumping the gun by focusing on COVID booster shots?

Branche: No. I think the goal is to be prepared to boost people when we need to. Pfizer is responding to early signals from Israel that suggest vaccine efficacy may start waning, slightly, as soon as six months after vaccination. That possibility, combined with new and more transmissible variants, could make a booster shot beneficial in the fall, or perhaps later.

Why did the CDC and FDA respond the way they did?

Branche: The CDC and FDA are pointing out that we just don’t have enough data yet to know if and when booster shots will be needed – and most scientists would agree. The vaccines have only been available to some communities for six to eight months, which isn’t enough time to definitively answer these questions.

Expressing different opinions now won’t prevent scientists from reaching consensus as more data becomes available.

Can I be a part of COVID vaccine booster studies?

URMC and Rochester Regional Health are conducting a number of studies around COVID vaccine booster shots. For more information about the studies, visit: Bring Roc Back or call (585) 273-3990.