Each week, OMRF physician-scientist Dr. Eliza Chakravarty opens “Adam’s Journal” to answer a medical question from OMRF Senior Vice President and General Counsel Adam Cohen.
I participated in the clinical trials of the Pfizer Covid-19 vaccine, so it’s now been more than nine months since I received my second shot. Will I need a booster shot? If so, when, and should it be another dose of the Pfizer vaccine I received last summer?
Dr. Chakravarty Prescribes
For months, scientists have speculated whether a third dose of Pfizer and Moderna’s Covid-19 vaccines might be necessary. The concern is that immunity may fade, or variants of the virus may render the vaccines less effective.
Studies show both the Pfizer and Moderna regimens provide a strong immune response for at least six months. Each of the vaccines approved for use in the U.S. has also so far proven effective against the variants in preventing severe illness and death.
However, because you received your vaccination so early, you’re out beyond the data. Which means that we don’t yet know the answers to your questions. But, eventually, we will.
In February, Pfizer began testing a third dose of its vaccine in trial participants to understand how another shot would impact long-term immune response. Results from the studies aren’t published yet, but last month, the company’s chief executive said a third dose was likely to be needed between six and 12 months from the initial series, followed by annual vaccinations.
Separately, the pharmaceutical companies are testing boosters modified for specific variants. Whether we’ll need a new shot formulated for a particular strain is unknown, but the companies want to be ready.
If studies determine that a third booster dose is needed, a formal recommendation will come from the U.S. Centers for Disease Control and Prevention. And if that happens, I suspect you’ll want to stick with the manufacturer of your original Covid-19 vaccine. While mixing and matching these vaccines is being studied, safety data isn’t available yet.
Do you have a health query for Dr. Chakravarty? Email firstname.lastname@example.org and your question may be answered in a future column!