TOKYO: The Japanese health ministry gave its approval Monday to improved COVID-19 vaccines effective against omicron variants.

The government is expected to begin administering the improved vaccines, developed by Pfizer Inc. and Moderna Inc., as early as next week.

The improved vaccines will first be used as a replacement for conventional versions in fourth shots for elderly people and others, expected to total about 15 million.

From mid-October, coverage will be expanded to include people aged 12 and older who have completed their second shots.

Overseas clinical trials have shown that a fourth shot using the improved Pfizer vaccine produced 1.56 times more neutralizing antibodies than a conventional vaccine and that the improved Moderna vaccine 1.75 times more.

A health ministry expert panel said no serious safety concerns were identified with the improved vaccines.

The bivalent vaccines, developed based on the BA.1 omicron subvariant, are believed to be effective against the currently dominant BA.5 subvariant as well.

The Pfizer vaccine will be given to people aged 12 and older, while the Moderna vaccine is for those aged 18 and older.

A total of roughly 30 million doses will be supplied by the two U.S. drugmakers from Sept. 19, with enough for all eligible people arriving in Japan by the end of next month.

The health ministry panel decided on Sept. 2 that the improved vaccines are expected to be more effective in preventing severe symptoms than conventional versions.

The panel also said that the improved vaccines are expected to be effective in preventing infections and the development of symptoms, although possibly for only a short period of time.

JIJI Press