Japan will start preparing to administer fourth doses of coronavirus vaccines, a health ministry subcommittee agreed Thursday, after the government said it would buy additional vaccine doses from two U.S. pharmaceutical companies.

The details, including whether to actually administer the additional booster shots and who would be eligible, will be determined later.

The agreement among subcommittee members came after the government said it had agreed to procure a total of 145 million vaccine doses from Pfizer Inc. and Moderna Inc. to prepare for the rollout of fourth shots.