Japan has administered more than 100 million doses of COVID-19 vaccines and surpassed the U.S. in the proportion of older people fully vaccinated, according to government figures released Tuesday.

The vaccination milestone comes as Japan, like many other nations, is in the midst of a fresh wave of coronavirus infections attributed to the delta variant. Japan and Tokyo have reported record daily infection numbers for several days this month, as the Summer Olympics drew to a close.

Most of the new infections have been among those in their 20s and 30s, showing the impact of the gap in inoculation rates between older people and the rest of the population. As vaccinations open up to younger demographics, experts have expressed concern about hesitancy among younger people, who are less likely to get serious symptoms from COVID-19.

As of Tuesday, Japan had administered 102.9 million doses and 81.6% of its residents age 65 and above were fully vaccinated, according to the Prime Minister’s Office. That’s higher than the 80.4% of the same age group fully vaccinated in the U.S., according to CDC data.

But Japan also has the lowest rate among the Group of Seven advanced nations of its population overall being fully vaccinated at 32.9%. That compares with 50.8% in the United States and 59% in the United Kingdom, according to the Johns Hopkins University’s vaccine tracker.

A poll carried out by public broadcaster NHK from Aug. 7-9 found 75% of respondents thought Japan’s vaccine rollout was "slow,” while only 18% said it was "smooth.”