Live updates: follow the latest news on Omicron
Moderna has enrolled its first participant in a clinical trial of its Omicron-specific vaccine booster, in another step towards fighting the highly transmissible variant that has spread around the world in weeks.
Moderna and rival Pfizer-BioNTech are rushing to test Omicron-specific vaccines in case they are needed as the coronavirus variant continues to spread around the globe.
On Tuesday, Pfizer said it had began a 1,400-person study of a messenger-RNA shot aimed at Omicron.
The Moderna study will test its booster, called mRNA-1273.529, in 600 adults who have received its existing vaccine, including 300 who have received just two doses and another 300 who have also received a third shot.
The trial will examine the safety and the immune response generated by the Omicron-specific shot.
Vaccine makers are tackling what kinds of shots may be most effective as the coronavirus continues to mutate.
Omicron-specific boosters are one possibility; another is a multivalent vaccine that would induce protection against several strains.
Other strategies include broad-acting vaccines that would work against even more mutations.
Moderna is testing the new booster because of “the long-term threat demonstrated by Omicron’s immune escape", chief executive Stephane Bancel said.
“We are also evaluating whether to include this Omicron-specific candidate in our multivalent booster programme.”
The company said it was reassured by a report in the New England Journal of Medicine showing patients who had received three doses of Moderna’s existing vaccine still had neutralising antibodies against Omicron six months after the third shot.
But after the booster, levels of Omicron-fighting antibodies declined faster than those against the original virus strain.