Lauran Neergaard | Associated Press

Moderna says its experimental COVID-19 vaccine that combines its original shot with protection against the omicron variant appears to work. COVID-19 vaccine makers are studying updated boosters that might be offered in the fall.

Pfizer says a booster dose of its COVID-19 vaccine may protect against the new omicron variant.

The Centers for Disease Control and Prevention has endorsed COVID-19 booster shots for millions of older or otherwise vulnerable Americans. The move opens a major new phase in the U.S vaccination drive against the coronavirus.

The vaccine maker said Monday it plans to seek authorization for this age group soon in the U.S., Britain and Europe — a key step toward beginning vaccinations for youngsters.

The world’s leading COVID-19 vaccines may offer lasting protection that diminishes the need for frequent booster shots.