Established last month by the Defense Ministry, the centers in Tokyo and Osaka originally gave shots to people aged 65 and older living in seven prefectures in the metropolitan and Kansai areas.
The ministry expanded the scope last week to accept people from nationwide and also decided Tuesday to remove the age restrictions in an effort to speed up vaccination.
The ministry said it will start accepting reservation requests for vacant slots available at the venues from midnight Tuesday.
The centers, which can inoculate up to 10,000 people a day in Tokyo and 5,000 at the Osaka venue, will vaccinate people with US pharmaceutical company Moderna Inc.'s two-dose vaccine.
According to the ministry, at the Tokyo center, about 87,000 of the 120,000 vaccination slots for the two-week period through June 27 were unfilled as of 10 a.m. Tuesday, while about 33,000 of the 60,000 slots remained vacant at the Osaka center.
Some municipalities have already started vaccination of people aged under 65 at their own venues, while companies and universities were recently given the greenlight to administer vaccinations on site.
