A primer on what we know about mixing and matching Covid vaccines

 

Later this week an expert committee that advises the Centers for Disease Control and Prevention will hear about the results of a clinical trial that could influence how Covid vaccines are used in this country at some point in the future. The trial, conducted by the National Institute of Allergy and Infectious Diseases, is a so-called mix-and-match trial, testing the Covid vaccines authorized in the U.S. in combinations with each other.

The goal of the trial was to see whether using a different vaccine as a booster shot improves protection. So does getting a dose of Pfizer vaccine after getting a single dose of Johnson & Johnson’s vaccine trigger production of more antibodies than a second dose of the J&J would? Are the messenger RNA vaccines made by Pfizer and Moderna virtually interchangeable, or does switching even there produce a broader set of immune responses?

This isn’t theoretical. The booster shot most vaccinated Americans are in the process of getting or booking may not be the last needed. Figuring out how to optimize use of the current generation of Covid vaccines is critical, a number of experts have told STAT.

 

 

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