Japan's state-run mass coronavirus vaccination centers will start inoculating people between the ages of 18 and 64 on Thursday in an attempt to fill vacant appointment slots, the ministry in charge of operations said Tuesday.

The centers in Tokyo and Osaka were set up last month by the Defense Ministry to vaccinate people age 65 and above living in seven prefectures in the metropolitan and Kansai areas.

But last week, with appointments remaining largely unbooked for two weeks through June 27, the ministry expanded the scope to vaccinate eligible people from anywhere within the nation.