US regulators authorized a second round of omicron-targeted boosters for individuals older than 65 and those with weakened immune systems.

The Food and Drug Administration said Tuesday that older adults can get another updated COVID-19 booster as soon as four months after their first bivalent booster dose, while immune-compromised people can get one at least two months after their last dose. Additional doses for those who are immune-compromised can be administered at the discretion of their health-care provider, the FDA said.

The agency is also simplifying the vaccination schedule by authorizing the bivalent shots made by Pfizer and Moderna to be used for all COVID vaccine doses and has phased out the vaccines that were used at the beginning of the pandemic. A group of advisers to the Centers for Disease Control and Prevention are meeting today to discuss the FDA's changes.