URMC researchers to study mixing COVID vaccines

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An upside of the unprecedented speed with which vaccines to fight the SARS-CoV-2 coronavirus were developed is that we are farther along in taming COVID-19 than initially expected. A downside is that there is a lot we don’t know about how the vaccine will work going forward. 

A study getting underway by University of Rochester Medical Center researchers, designed to examine what happens when you mix and match vaccines, hopes to fill in some of the blanks. 

Currently approved vaccines are 70 percent to 95 percent effective at preventing or diminishing the effects of a COVID-19 infection. But if asked how long will immunity last, whether booster shots will be needed to maintain effectiveness, how often such shots might be needed or what might happen if someone immunized with a Moderna, Pfizer-BioNTech or Johnson & Johnson vaccine gets a booster shot of a different vaccine, experts say the answer in each case is the same: We simply don’t know.

When it first became evident that COVID would be global pandemic in early 2020, experts predicted that it would take 18 months to three years to develop a vaccine. It took less than year for not just one but multiple safe and effective vaccines to be developed. 

Part of the reason for that speed is that research into the emerging mRNA technology behind the Pfizer and Moderna vaccines happened to be at a point where it could be quickly and effectively ramped up. 

But another reason is that government regulators greatly shortened the approval period for the new vaccines, forgoing tests that would have answered the questions scientists like URMC researchers Ann Falsey M.D. and David Dobryznski M.D. are hoping to answer with what Falsey says they are calling “the mix-and-match trial.”

In the study, researchers are looking for unvaccinated volunteers or volunteers who have received an initial shot within the previous 12 to 20 weeks. Participants need to be 18 or older. The study hopes to recruit 50 volunteers locally. 

Unvaccinated participants will receive the Moderna vaccine and then a booster dose of either the same vaccine or a Moderna variant vaccine 12 weeks later. Volunteers who have already been vaccinated with the either the Moderna, Pfizer-BioNTech or Johnson & Johnson vaccines will receive a booster dose of the Moderna vaccine. The local study is part of 10-site, 500-participant National Institutes of Health program.  

So many questions are still hanging because vaccines have not been in use long enough to answer them. 

Which is why Falsey says, “we’re pretty excited about this study. I think that it’s going to address some of the most commonly asked questions that we get.” 

To people who want to know if they will need a booster, “my answer is: we really don’t know,” says Falsey, a co-director of the URMC’s Vaccine Treatment and Evaluation Unit. To those who want to know if it’s safe to mix different type of vaccines, she replies, “probably,” adding the caveat that “we really should do some studies.”

Other questions this trial could help to answer include how effective currently approved vaccines might be against newly emerging and more easily transmitted SARS-CoV-2 variants. All three vaccines not in use in the United States appear so far to work well against variants that have emerged in the United Kingdom and India. But new variants could require development of new vaccines or different versions of existing ones.

A silver lining of sorts of the coronavirus pandemic has been a steep drop in the usual winter upsurge of flu cases, which experts largely attribute to the greater prevalence of mask wearing, hand washing and social distancing COVID has engendered. Some speculate that the dearth of flu cases might have led to the complete elimination of some flu strains.

Such an outcome would be nice, says Dobryznski, but it is not one he is counting on. Neither does he see COVID disappearing in the foreseeable future.

“I hope I’m wrong,” says the researcher. “But I expect we’ll be living with the virus for the next few years, if not longer.” 

Will Astor is Rochester Beacon senior writer. Volunteers can sign up here or by calling (585) 273-3990.

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