Moderna vs. Pfizer: Is it OK to mix and match the updated COVID-19 booster shots?

LOS ANGELES — As residents prepare to roll up their sleeves for a third, fourth or even fifth dose of COVID-19 vaccine, some may be wondering: Do I need to stick with the same brand, or is it safe to mix it up?

When it comes to the new COVID-19 omicron bivalent booster, the answer is that you can mix and match.

You can get either the Pfizer-BioNTech or Moderna version, regardless of which shot you previously received.

“The best booster for you is the one that you can get — either the Pfizer or the Moderna can be used, and they can be mixed or matched,” said Dr. Robert Kim-Farley, epidemiologist and infectious disease expert at the UCLA Fielding School of Public Health. “If there’s shortages of one, you should not have hesitancy to take the other.”

Say a person has received three doses of the Moderna shot. Should they stay with Moderna or mix it up with a Pfizer booster?

The effect on the body’s immune system should be similar either way, UC San Francisco infectious disease expert Dr. Peter Chin-Hong wrote in a tweet.

“It’s OK to mix and match Moderna and Pfizer,” Dr. Ralph Gonzales, associate dean for clinical innovation and chief innovation officer for UC San Francisco, said at a campus town hall last week. “I just got my Moderna two days ago and it was an interesting experience. I definitely felt a stronger response with the Moderna — having had Pfizer before — but either combinations are fine.”

The U.S. Food and Drug Administration actually allowed mixing and matching of COVID-19 booster doses starting last year, after it allowed people to get their first booster dose. Despite having the choice, though, a lot of people ended up staying brand loyal.

But others switched it up, either as a matter of preference, availability or recommendation. Many of those who initially received the single-dose Johnson & Johnson vaccine, for instance, opted for Pfizer or Moderna come booster time.

When some people — those age 50 and up and the immunocompromised — became eligible for a second conventional booster shot earlier this year, some decided to go with the other brand. Dr. Robert Wachter, chair of the UC San Francisco Department of Medicine, in April decided to go with Moderna for his fourth shot after three consecutive Pfizers.

“I saw it as a tossup,” he tweeted at the time.

The updated omicron bivalent booster shot is available to those age 12 and up. Adults can choose from either Pfizer or Moderna; adolescents age 12 to 17 are only eligible for Pfizer.

L.A. County Public Health Director Barbara Ferrer said there’s some expectation that the updated booster will be available for children age 5 to 11 perhaps as soon as October.

Officials are urging people to get the updated booster, which they expect will reduce the risk of infection. It’s called a bivalent shot because it’s designed to protect not only against the original coronavirus strain, but also the latest omicron subvariants that have dominated the nation this summer, including BA.5.

“The bivalent boosters provide protection against the subvariants that are currently circulating at the highest levels, and they’re going to be one of our best tools in planning for a safe, healthier and happier fall and winter holiday season,” Ferrer said Thursday.