Japan's COVID-19 vaccine minister on Tuesday warned local governments against letting doses go to waste as the country expands its inoculation campaign to older people.

The warning from Taro Kono came as he disclosed that up to five doses of Pfizer Inc.'s vaccine were discarded Monday due to last-minute cancellations.

Kono suggested that local authorities can be flexible in using doses that become available as a result of people canceling their vaccination appointments, such as by allocating them to those age 64 or younger or those who live outside their municipalities.

"No problem, there are no restrictions (on such usage)," Kono said at a news conference.

On Monday, an initial 1,139 people age 65 or older received shots of the vaccine as part of the second group to be vaccinated following health care workers, according to the government.

Amid growing concerns over a fourth wave of infections, the government is seeking to secure enough shots of the vaccine for roughly 36 million older people and deliver them to municipalities by late June.

Older people, who account for around 29% of the population, tend to develop more serious symptoms than younger people when infected with the virus.

The vaccination rate in Japan lags far behind those of other countries such as Britain and the United States since Japan relies entirely on imports for its coronavirus vaccine supply.

Following older residents, people with pre-existing conditions, such as diabetes, and those working at care facilities are slated to get shots next, after which vaccinations will eventually be extended to the rest of the population.