Researchers explore the possible benefits of pairing doses from two different COVID-19 vaccines

Published: May. 26, 2021 at 9:36 PM EDT
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LOUISVILLE, Ky. (WAVE) - Many things can be mixed and match but, what about vaccines? It’s been done before and now scientists are exploring the possible benefits of pairing doses from two different Covid-19 vaccines.

Right now, there is guidance from the CDC on mixing vaccines.

“The CDC and the manufacturers don’t really want you to mix the vaccines,” Dr. Mark Burns from UofL Health said.

If you got the Moderna vaccine, your second dose should be the Moderna vaccine. The same goes for Pfizer’s shot.

The CDC, says only under “exceptional circumstances” that it’s OK for people to receive one shot of Pfizer vaccine and one shot of Moderna at least 28 days apart. But, the possibility of mixing the vaccines is being explored.

“They are starting to do some studies,” Dr. Sarah Moyer from Louisville Metro Public Health and Wellness said.

Burns says mixing vaccines are primarily done by countries overseas where there’s a shortage of COVID-19 vaccines and significant delays in shipments.

One study out of the UK says mixing coronavirus vaccines may increase the short-term side effects. In the British study, 830 people ages 50 and older were given a dose of the AstraZeneca vaccine, followed by the Pfizer shot or vice-versa or two doses of the same vaccine.

Those who received mixed doses were more likely to develop mild to moderate side effects compared to those who got the same vaccine. The researchers say the adverse reactions were found to be short-lived and there were no other safety concerns.

Burns said he’s also seen reports of a study from Spain. Preliminary results from the Spanish study suggest mix and matching vaccine doses may increase antibodies.

“People had gotten the Astrazeneca vaccine and the Pfizer vaccine,” Burns said. “The antibody response was much more profound after they had received this Pfizer vaccine.” Which is good news.

All of this research is important because we still don’t know if or when we will need a booster shot.

“That may change over the summer or how COVID responds to the vaccines internationally, there is a chance,” Moyer said.

One thing is for certain, we are learning about all of this in real-time and this is an area of active research.

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