The U.S. Food and Drug Administration on Monday approved and authorized updated COVID-19 vaccines by Moderna Inc (MRNA  ) and partners Pfizer Inc (PFE  ) and BioNTech SE

(BNTX  ) aimed at better countering circulating viral strains, including the omicron variant XBB.1.5.

The FDA said it is confident in the updated vaccines' safety and efficacy. The vaccines are expected to effectively guard against current COVID-19 strains.

Both Pfizer and Moderna confirmed the updated vaccines will be ready by the fall, with the FDA expecting their release in the near future.

Research indicates he updated vaccines offer a comparable level of protection against current viral strains, including EG.5 and BA.2.86, as the older versions did against earlier strains.

The Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices is set to meet to discuss clinical recommendations on the updated vaccine's recipients, including considerations for vulnerable groups like the immunocompromised and elderly.

While the FDA approved the updated vaccines from Moderna and Pfizer, they will not be available immediately to Americans. A CDC advisory panel is scheduled to meet to decide on the use of the vaccines.

Once the CDC director gives a nod to any recommendations, vaccination distribution can start across various sites.

Shares of Novavax Inc (NVAX  ), a company also in the race to update its COVID-19 vaccine, fell almost 13% after the approval of Pfizer's and Moderna's vaccines. Novavax's vaccine, which uses protein-based technology, is still awaiting FDA approval.