View Comments If you don't know whether you need a COVID-19 vaccine booster shot, don't worry. You don't – at least not now. And the vaccine experts don't know yet whether you ever will. But the team at the Gamble Vaccine Research Center at Cincinnati Children's Hospital Medical Center is among those working to find out. The center began testing on a Pfizer COVID-19 booster shot this week. Booster shots, as their name suggests, are used to boost the antibodies in the blood created by previous vaccines in a person. Because, over time, the antibodies decrease. But Dr. Robert Frenck, chief investigator for the trial and director of the vaccine research center, stressed that the best way to prevent COVID-19 infection is still by getting vaccinated.