LONDON >> The European Medicines Agency has recommended the authorization of a tweaked booster dose of the Pfizer-BioNTech coronavirus vaccine that includes protection against two of the latest versions of omicron, as countries look to bolster their immunization programs ahead of winter.

The EU regulator said today that laboratory studies suggest the combination vaccine — which targets both the original COVID-19 virus as well as the omicron subvariants BA.4 and BA.5 — should trigger an effective immune response. The vaccine is expected to be as safe as the original version, but the agency will continue to track its rollout globally since the data is limited.

The U.S. Food and Drug Administration gave the modified vaccine shot the green light last month.

According to the World Health Organization, the BA.5 version of omicron is responsible for most of the COVID-19 spreading globally; it made up about 87% of all virus sequences shared with the biggest public database.

Earlier this month, the European Medicines Agency also cleared two combination vaccines made by Pfizer-BioNTech and Moderna Inc. which aimed at protecting against the earlier omicron subvariant BA.1.

It’s unclear how well the updated boosters will work since experts are still gathering data. But there’s evidence that they are safe, so waiting for more study on their effectiveness would risk another mutation appearing before people are immunized.

Scientists warn that the coronavirus will linger far into the future, partly because it is getting better and better at getting around immunity from vaccination and past infection.

Globally, coronavirus cases and deaths have been dropping for weeks, but experts expect a surge of hospitalizations and deaths with the coming winter in the northern hemisphere. So far the virus has killed over 6.5 million people worldwide.