Britain on Monday became the first country to authorize a coronavirus vaccine that targets two variants, the original virus and Omicron, the variant that became dominant over the winter.
Half of each dose of the Moderna-made vaccine will target the original variant, and the other half will target Omicron. In clinical trials, the vaccine, an updated version of Moderna’s original Covid vaccine, generated a good immune response to these two variants, as well as the BA.4 and BA.5 subvariants in adults, researchers found.
Dr. June Raine, the chief executive of Britain’s Medicines and Healthcare Products Regulatory Agency, said she was pleased that the new booster vaccine met the regulator’s standards of safety, quality and effectiveness. The decision was endorsed by Britain’s independent expert scientific advisory body, the Commission on Human Medicines.
“The first generation of Covid-19 vaccines being used in the U.K. continue to provide important protection against the disease and save lives,” Dr. Raine said. “What this bivalent vaccine gives us is a sharpened tool in our armory to help protect us against this disease as the virus continues to evolve.”
Side effects were the same as those seen for the original Moderna booster dose and were typically mild, with no serious safety concerns, British regulators said.
The emergence of highly contagious Omicron subvariants this spring have appeared to reduce the protection offered by the Pfizer-BioNTech and Moderna vaccines against Covid hospitalizations, with more vaccinated people admitted to the hospital with Covid than they had been during the winter Omicron wave. But booster shots have raised people’s levels of protection, scientists from the U.S. Centers for Disease Control and Prevention said last month. The C.D.C. recommends that people receive booster shots as soon as they are eligible.
An advisory panel of the Food and Drug Administration said in June that vaccine manufacturers should tailor shots to the newest variants, but it was unclear whether those shots would arrive in time in the United States to forestall a fall surge.
Britain has high vaccination rates overall, with 76 percent of the population fully vaccinated and 60 percent having received an additional dose. By comparison, in the United States, 67 percent of the population is fully vaccinated, and just 32 percent have received an additional dose. Globally, 64 percent of the population is fully vaccinated, according to The New York Times’s Covid vaccine tracker.