How Pfizer and BioNTech Modified Covid-19 Vaccines for Fall Boosters

Before new versions of the Omicron strain took hold in the U.S., Pfizer Inc. and BioNTech SE had begun tinkering with their widely used Covid-19 vaccine. In May, researchers tracking how coronavirus strains behave saw the potential for Omicron subvariants to predominate. Just in case, the companies started building blueprints of shots reformulated to target BA.4, BA.5 and other substrains, and laid the groundwork for testing them. The preparations proved prescient, a big reason, along with manufacturing enhancements, that tens of millions of doses of Pfizer-BioNTech boosters modified to target BA.4 and BA.5 are now rolling out. “If we’re going to be ready for the disease and its migration, I don’t have the time to wait,” said Mike McDermott, Pfizer’s chief global supply officer.