x
Breaking News
More () »

Why not mix and match COVID vaccines?

There have been no clinical trials to test what would happen if you got a Moderna vaccine followed by Pfizer.

ATLANTA — Nearly half of all Americans have received at least one dose of the COVID-19 vaccine, a situation that does not allow mixing and matching.

A shot of Moderna needs to be followed by another shot of Moderna. A Pfizer shot means a second dose of Pfizer.

Why?

“From a scientific point of view, they’re likely to be ok,” says Dr. M.G. Finn of Georgia Tech. “but we don’t know for sure.”

The vaccines are being administered according to FDA’s Emergency Use Authorization.

“What’s authorized is using Pfizer with Pfizer, Moderna plus Moderna,” says Dr. Mark Tompkins of the University of Georgia’s Center for Vaccines and Immunology.

There have been no clinical trials to test what would happen if you got a Pfizer vaccine followed by Moderna. Clinical trials test the effectiveness and safety of vaccines.

Dr. Finn says all of the available vaccines work to inhibit the ability of the coronavirus to latch onto our cells.

“So in some sense they’re similar, but they differ in how they deliver that information to the body, and that matters a lot,” says Finn.

Dr. Tompkins tells us there have been clinical trials that mixed vaccines battling other illnesses.

“You can sometimes generate better responses as well as more diverse responses,” says Dr. Tompkins. “So there are some potential advantages there.”

To offer flexibility to its vaccine program, the United Kingdom is researching the effectiveness of combining two different COVID vaccines.

There’s no indication yet that the U.S. is planning similar research.