President Joe Biden said U.S. regulators are looking at administering Covid-19 booster shots five months after people finish their primary immunizations, moving up the expected timetable for a third shot by about three months.

Biden, who was speaking with Israeli Prime Minister Naftali Bennett on Friday, said health officials were considering following that country’s lead on boosters.

“We’re considering the advice you’ve given that we should start earlier,” Biden said, adding that officials are debating whether the timeline should be shorter. “Should it be as little as five months and that’s being discussed.”

Approval of the booster shots is expected to come sometime around Labor Day after federal health officials have time to review data from other countries and vaccine manufacturers that indicated booster dose efficacy six months after a previous dose.

In adults age 60 and older, a booster dose of a Covid-19 vaccine provided 4x as much protection against infection with the delta variant than the previous two-dose regimen, according to the Ministry of Health of Israel.

Distribution of the booster shots following Food and Drug Administration clearance and Centers for Disease Control and Prevention recommendation is expected to begin on September 20. The Biden administration and vaccine manufacturers have indicated that there should be enough doses for any fully vaccinated adult seeking a third dose.

Correction: This article was updated to correct the timing of when a potential third Covid dose might be administered. It’s five months after full immunization.