Lab studies had suggested that vaccine protection was lower against the XBB variants compared with prior variants, raising questions about how well the vaccines worked against these rising strains of the virus.

About 65% of Japan's population have received at least one Covid vaccine booster shot, compared to about 33% in the US, based on government data.

The updated shots target the widely circulating BA.4 and BA.5 Omicron subvariants as well as the original version of the coronavirus included in all previous Covid vaccines.

The committee voted 19 in favor and two against the measure after a day spent reviewing available data, including projections about future waves and early results from vaccine makers.

It says available evidence emerging from Israel and the UK shows a significant increase in protection against infection and severe disease following a booster dose in all age groups in the short term.