People wearing face masks ride bicycles as they cross an intersection near a shopping street in Tokyo on Thursday, July 15, 2021.

TOKYO — New coronavirus cases surged to 1,308 in Tokyo on Thursday, a six-month high, as fears rise of a possible dramatic increase that could flood hospitals during the Olympics that start in eight days.

Tokyo is under a fourth state of emergency, which began Monday and requires restaurants and bars to close early and not serve alcohol through the Olympics, which start July 23.

Thursday's tally is the highest since 1,485 were recorded on Jan. 21, when Japan was under an earlier state of emergency.

Tokyo Gov. Yuriko Koike noted that the largest increase in serious cases and hospitalizations was among people in their 50s and younger who are largely unvaccinated.

She expressed concern about the impact on the medical system as infections are propelled by the more contagious delta strain of the virus.

New daily cases have been steadily climbing since mid-June and experts say they could hit several thousand during the games.

Japan's slow vaccination rollout has improved dramatically since May, but is slowing again due to shortages of imported vaccines. The latest government data show 19.7% of the population is fully vaccinated.