A official said vaccine makers won't need to carry out fresh clinical trials to receive approval for booster shots they're updating for newer Omicron variants. Dr. Peter Marks, who runs the FDA's Center for Biologics Evaluation and Research, told the agency will use data from trials for vaccines that target BA.1 — the Omicron variant that caused a huge surge in infections last winter — as well as manufacturing data to assess the vaccines. Safety data and preclinical data from animal studies may also be used.
This week, the FDA asked vaccine manufacturers to modify booster shots to target the Omicron BA.4 and BA.5 variants in addition to the original strain of the virus. The agency hopes the updated boosters will be ready by the fall. "It's going to be really critical as we move into this fall where we've seen this evolution into BA.4/5, where we could see further evolution, to try to get as many people boosted as we can," Marks said.
The Centers for Disease Control and Prevention says BA.1 isn't circulating in the US anymore, but BA.4 and BA.5 now account for over 52 percent of COVID-19 infections in the country. Combined, they made up just 0.5 percent of cases in the US at the end of April.
Pfizer and Moderna this week clinical trial data which suggests versions of their shots that target BA.1 offered a stronger immune response than the initial COVID-19 vaccines. Those boosters did not perform quite as well against BA.4 and BA.5. However, the data showed that the immune response was still robust.