The government may start inoculating the public specifically against the omicron variant of the coronavirus by the end of September, rather than mid-October as originally planned, government sources have said.

U.S. pharmaceutical firms Pfizer and Moderna have each applied to the health ministry for the production and sale of their COVID-19 vaccines tailored for the highly transmissible variant. An expert panel with the ministry is expected to discuss soon whether they should be approved.

Health minister Katsunobu Kato stressed at a news conference on Tuesday that the government will work hard to make the additional inoculation happen sooner than planned, saying that many members of the public have high expectations for it.

The ministry panel this month decided to make omicron-specific COVID-19 boosters available to all who have completed at least the first two-shot regimen and to make preparations so the additional inoculation can begin in mid-October or later.

If health authorities approve the omicron boosters, their imports can begin by the end of September. The exact timing of the start of the additional vaccination, however, will depend on when imports can happen and the degree of preparations local authorities will make ahead of the new drive, one of the sources said.

The omicron boosters have properties derived from the BA.1 subvariant as well as the original virus that spread early in the pandemic. They are said to work effectively against the BA.5 subvariant now prevalent in Japan.

Japan reported 152,546 new virus cases on Tuesday, down close to 56,000 from a week ago. Among the nation's 47 prefectures, Osaka had the largest number of cases at 16,364, followed by Tokyo at 14,219.

New COVID-19 deaths reached 319 nationally.

Tokyo's count was about 7,500 fewer than on the same day last week.