Israel could be one of the first countries to begin administering a fourth dose of COVID-19 vaccine to individuals over 18 after a positive advisory committee decision.

Before the decision becomes binding, the director of Israel’s Ministry of Health, Nitzan Horowitz, must sign off on the recommendation.

If implemented, Israeli adults would be eligible for a fourth dose five months after receipt of the third dose or recuperating from a COVID-19 infection.

In making its decision, the panel cited data from Sheba Medical Center that shows a fourth dose of the Pfizer-BioNTech COVID-19 vaccine yields a three- to five-fold increase in protection against severe disease. A fourth dose, however, is unlikely to offer robust protection against infection.

While Israel has already begun providing a fourth dose to immunocompromised people, healthcare workers, and those over 60, Horowitz recently stated that an additional dose would likely be unnecessary for most individuals.

Israel is currently encountering record numbers of COVID-19 infections, with the number of hospitalized patients eclipsing previous records of the pandemic.

Whether a fourth dose can help Israel reverse the trend remains unsettled, according to Jonathan Sterne, professor of medical statistics and epidemiology at the University of Bristol, UK. While data suggest a third dose of COVID-19 vaccine provides a significant increase in protection, “we have very little evidence” related to fourth doses of the vaccine from studies of immune function or observational studies of clinical events, Sterne told The Lancet.

The WHO has criticized blanket booster programs, arguing that distributing vaccines in the developing world should be a higher priority. The organization recently concluded there was no need to provide booster doses to healthy children and adolescents.