Different vaccine types OK for first, second doses if need be, CDC says

A change in vaccine guidance is coming from the top. In rare cases, the CDC says the two currently approved mRNA coronavirus vaccines can be used interchangeably.

But this doesn’t mean people should seek to get a different manufacturer’s vaccine from their first administered dose. If you can get two doses of the same vaccine, that’s the optimal pathway to completing the vaccine process.

“There may be some folks, especially snowbirds in our area, that are getting a vaccine here, going back home to complete their series or something like that, and may run into a situation where Moderna may not be available, but Pfizer is,” explained Jospeh Pepe, the administrator for Florida Department of Health in Charlotte County.

Despite the new guidance, for some in Southwest Florida, getting the same vaccine for the first and second doses is still the only option they’ll accept.

“We finally wound up being successful with the Lee County system after 249 calls in a row,” Howard Futterman said.

That was just scheduling the first dose for Futterman.

Futterman is now among one of thousands of Southwest Florida seniors waiting for his second dose, and he has new concerns.

“We had a lot of concern about whether they would have the supply,” Futterman said.

New CDC guidance answers both concerns. The update says — in exceptional situations — you can mix and match doses. Also, if there’s no way around it, you can schedule your second dose up to six weeks after your first.

You might be asking, when it comes to mixing and matching doses, what is an exceptional situation?

The CDC says it’s either when you don’t know which version you had first, or that version is unavailable.

Reactions to the new rules are mixed.

“Ideally, that scenario is to give people the vaccine that they started with the same manufacturer. So we’ve been sticking to that. I think, if we get into a bind, certainly the CDC guidance is what we’re going to follow,” Pepe said. “At the very least, it just gives us more options.”

“When Moderna and Pfizer did their clinical studies upon which they were approved, it was based on the waiting periods of either 21 or 28 days depending on whether it’s Pfizer or Moderna, and for the CDC to arbitrarily say, ‘Well, guess what? You can wait a month or two.’ I think that’s got no basis in science and I don’t believe it,” Futterman said. “It creates a lot of anxiety for the people who took the second shot as to whether they’re going to get it when they’re supposed to get it.”

Researchers, including Dr. Kartik Cherabuddi with UF Health, work to calm those concerns.

“If you look under the hood, both mRNA vaccines function the same way. I am not truly concerned about the safety in this scenario,” Cherabuddi explained. “If you don’t have the same kind of vaccine, I would just stress take the other vaccine as well, rather than forgo it completely.”

MORE: Interim Clinical Considerations for Use of mRNA COVID-19 Vaccines Currently Authorized in the United States