So far, more than 92 million Americans — 54 percent of those fully inoculated — have gotten Pfizer shots. Dr. Marks said that federal health agencies would continue to monitor the vaccine’s safety and that the F.D.A. in June attached warnings to the Pfizer-BioNTech and Moderna vaccines noting possible increased risk of those conditions after the second dose. Federal health officials said that both Pfizer-BioNTech and Moderna’s vaccines, which rely on similar technology, wane in potency over time. Boosters would only be warranted if the vaccines were failing to prevent hospitalizations with Covid-19, some of those experts have said.

Source: International New York Times August 23, 2021 09:54 UTC