New booster takes a dual approach
DEAR DOCTORS: How important is it to get the new COVID-19 booster? What’s in this new shot? Is it a good idea to switch up vaccine brands?
DEAR READER:
We think it’s important for everyone who is medically eligible to be fully vaccinated against COVID-19 and to remain up-to-date with boosters. And yes, this includes the new bivalent vaccine, which was authorized by the Food and Drug Administration at the end of August.
The latest data show that 90% of all new COVID-19 infections in the United States are now caused by omicron BA.5, the newest subvariant. That speaks to the fact that it is the most easily spread strain of the coronavirus to date. The vaccine booster that you’re asking about includes components of the original coronavirus that causes COVID-19 and the omicron variant that has become the dominant strain. The boosters have proven to be effective at preventing serious disease as well as helping to prevent against initial infection.
Vaccines work by training the immune system to recognize one or more specific molecular characteristics of an invader. This allows the body to quickly mobilize its defenses and neutralize the threat. In the case of the coronavirus that causes COVID-19, the identifying marker was the distinctive spike protein on its outer surface.
The new bivalent booster trains the immune system to recognize the spike protein from the original virus. It also includes a “tutorial” that’s specific to the omicron variant. By targeting these two distinct spike proteins — that’s the “bivalent” part of the
vaccine — the hope is that the new boosters will provide more robust protection.
Guidance is to begin with the original twodose series of the vaccine. You are considered to be up to date when you have completed the primary two-dose COVID-19 vaccine series and continue to receive the most recent booster dose that is recommended for you by CDC. This guidance varies by each person’s age, their specific COVID-19 vaccination history, the timing of their most recent dose and their medical history. Find information about vaccines, boosters and vaccination sites at vaccine.gov.
You asked about a mix-and-match approach to vaccines and boosters. This refers to switching between the Moderna and the Pfizer vaccines. There is evidence this practice may lead to enhanced immunity. People produce antibody responses from all three booster vaccines, no matter which vaccine they originally received. Studies show a subsequent dose of a different vaccine causes similar or higher antibody responses than a booster of the same vaccine. The FDA has authorized the use of mixand-match doses for currently available COVID-19 vaccines.