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 the elderly.

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.

Japan's COVID-19 vaccine minister Taro Kono speaks at a press conference in Tokyo on April 13, 2021. (Kyodo)

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 aged 64 or younger or those who live outside their municipalities.

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

On Monday, an initial 1,139 people aged 65 or older received shots of the vaccine as 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 seniors and deliver them to municipalities by late June.

The elderly, who account for around 29 percent 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 the elderly, 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.