Both of the mRNA vaccines available in the US are highly effective against severe COVID-19, but recent studies suggest that Moderna's elicits a stronger immune response and might be better at preventing breakthrough infections.

Changing to a different vaccine\n\n Some mix-and-match  studies have found that getting a different booster may even lead to a slightly better immune response than getting the same vaccine again. However, the data isn't fully clear. There isn't a clear advantage to switching between the Pfizer and Moderna vaccines.