The Food and Drug Administration (FDA) has issued emergency use authorizations for updated booster shots for both Moderna and Pfizer/BioNTech's messenger RNA (mRNA) COVID-19 vaccines. Both boosters are bivalent, containing components of the original virus strain and the currently prevalent BA.4 and BA.5 omicron variants. The shots are meant to function solely as boosters. People are eligible for the single bivalent booster shots if it has been at least two months since they have completed primary vaccination or have received a booster dose of the earlier approved vaccines. Moderna is authorized for people over age 18 and Pfizer/BioNTech for those over age 12.
Considering the speed with which the virus has been mutating and the increased infectiousness of the new variants, the FDA is approving COVID-19 booster shots in much the same way that it does seasonal influenza vaccines. Annually updated influenza vaccines do not need to undergo human clinical trials unless the vaccine makers have significantly changed the way they make the vaccines. The same situation applies to the COVID-19 boosters. The mRNA vaccines are essentially plug-and-play, where vaccine makers do not have to reformulate vaccines they already know work, but can instead switch out or add new mRNAs that produce the viral proteins that rev up our immune systems.
