Team USA’s top doctor told NBC News that out of the 613 athletes competing for Team USA in Tokyo at the Olympics, about 100 of them have not been vaccinated against COVID-19.

Dr. Jonathan Finnoff, chief medical officer of The United States Olympic & Paralympic Committee, estimated that 83% of the team is vaccinated — significantly higher than the national vaccination rate. 

“Eighty-three percent is actually a substantial number and we’re quite happy with it,” Dr. Finnoff said. 

According to data from the Centers for Disease Control and Prevention (CDC), 56.4% of the U.S. population has received at least one dose of a COVID-19 vaccine, with 48.8% fully vaccinated.

The IOC has estimated around 85% of residents of the Olympic Village are vaccinated; that's based that on what each country's Olympic committee reports but is not an independently verified number.

So far, the only American athletes known to have tested positive for COVID-19 are beach volleyball player Taylor Crabb, Women's 3x3 basketball player Katie Lou Samuelson and Kara Eaker, an alternate on the gymnastics team. The IOC has reported 13 positives among all athletes in Japan.

COVID-19 cases are on the rise in host nation Japan, with Tokyo reporting nearly 2,000 new cases one day before the games were set to kick off, the highest single-day average since January – and health experts warning that those infections are likely to continue to worsen in the coming weeks.

“The best thing to do is to assume everyone’s at risk, and reduce risk by introducing Covid mitigation measures that we know work,” Dr. Finnoff said of the games' COVID-19 safety measures.

Just over 23% of Japan's population is fully vaccinated against COVID-19.

The Associated Press contributed to this report.