The first doses of Pfizer Inc.’s COVID-19 vaccine will begin to be administered to 40,000 essential workers across 100 medical facilities on Wednesday, Taro Kono, the Cabinet minister in charge of vaccines, said during a news conference Tuesday.

The same workers will receive their second dose beginning March 10.

Kono said it is possible that other medical workers — those who do not fall into the initial category — could receive their first dose before March 10 once second doses for essential workers are secured.