TOKYO (REUTERS) - Four infections with the Omicron variant of coronavirus have been confirmed in the Japanese capital, its governor Yuriko Koike, said on Friday (Dec 24).

One was in a person who had not travelled overseas and was a case of suspected community transmission, she added.

Japan has been looking to speed up a booster programme that has covered just 0.3 per cent of the population so far.

Its health ministry said on Friday it agreed to buy a further 18 million doses of Moderna's Covid-19 vaccine.

As concerns grow about the increasing spread of the Omicron variant of coronavirus, Prime Minister Fumio Kishida unveiled a plan last week to speed up booster doses for about 31 million healthcare workers and at-risk elderly people.

The purchase in the first quarter of 2022 will take to 93 million the total of Moderna doses available next year, the ministry said in a statement.

The Moderna shots are to be imported by Takeda Pharmaceutical, which has also contracted to sell 150 million doses of the Novavax Inc vaccine to the government.

Japan is also set to receive 120 million doses of the Pfizer-BioNTech vaccine, used for the majority of its inoculations until now.

After a relatively late start, Japan has fully inoculated almost 80 per cent of its population of 126 million, the highest such rate among Group of Seven economies, but just 0.3 per cent have received a third dose as a booster.