Vaccine COVID Ba 2

About Vaccine COVID Ba 2

The Omicron BA 2 variant emerged in early 2022, followed by BA 4 and BA 5. These variants showed significant immune escape from original vaccines. Pfizer and Moderna developed bivalent boosters targeting the original strain and BA 4/BA 5. The FDA authorized bivalent boosters in August 2022 based on immunogenicity data without new clinical trials. The rapid authorization demonstrated the flexibility of the regulatory process. Bivalent booster uptake was disappointing, with only roughly 15 percent of eligible Americans receiving the updated booster by end of 2022. Subsequent variants including XBB and JN 1 required further vaccine updates. In 2023, the FDA moved to annual COVID vaccine updates similar to the flu vaccine process. The monovalent XBB 1 5 vaccine was authorized in September 2023. Vaccines updated for the JN 1 lineage were authorized in August 2024.