Moderna announces step toward updating COVID shots

Moderna hopes to offer updated COVID-19 boosters in the fall that combine its original vaccine with protection against the omicron variant.

Today's COVID-19 vaccines all are based on the original version of the coronavirus. But the virus continues to mutate, with the super-contagious omicron variant and its siblings the latest threat. Before omicron came along, Moderna was studying a combination shot that added protection against an earlier variant named beta. It said people given that beta-original vaccine combination produced more antibodies capable of fighting several variants — including omicron — than today's regular booster triggers. Now Moderna is testing a bivalent shot that better targets omicron — it includes 32 of that variant's mutations. Studies of two booster doses are underway in the U.S. and Britain; results are expected by late June.