U.S. health regulators are looking at authorizing a potential fourth dose of a COVID-19 vaccine in the fall, the Wall Street Journal reported on Saturday, citing sources familiar with the matter.

The Food and Drug Administration has been reviewing data to authorize a second booster dose of the messenger RNA vaccines from Pfizer Inc and partner BioNTech SE and vaccines from Moderna Inc, the report added.

The FDA did not immediately respond to a request for comment.

The agency last month cut the interval to get a booster dose of COVID-19 vaccines from Pfizer and BioNTech as well as from Moderna, in a bid to provide better protection sooner against the Omicron variant. 

The planning is still in early stages, and authorization would depend on determinations as to whether the second booster should be authorized for all adults or particular age groups, and whether it should target the Omicron variant or be formulated differently, the report said.

It added that no decision was final and that it could be necessary to make booster shots available earlier if a new variant appears.

The United States reported 2,323 COVID-19 deaths on Friday, bringing the total count to 936,523. 

(Reporting by Nishit Jogi in Bengaluru Editing by Matthew Lewis) ((Nishit.Jogi@thomsonreuters.com;))