The U.S. Olympic and Paralympic Committee’s top doctor said Monday that some American athletes have complained about the organization’s new requirement that everyone using its facilities or participating in an event, including the Beijing Winter Olympics, must be vaccinated.

“The response is as you would expect: Within our general population, there are some people who are extremely happy that they introduced this policy,” Jonathan Finnoff, the USOPC’s chief medical officer, said during the organization’s media summit. “Then there are others who are upset and would not like to have any mandate regarding vaccinations.”

Finnoff added that the number of athletes who have questioned the mandate “is a very small minority.”

He said he and his staff are talking to those athletes in one-on-one conversations to “talk through why they’re disappointed and why we made this decision.”

The USOPC’s leadership announced the mandate last month, just days before Beijing organizers and the International Olympic Committee announced their own more restrictive measures that Finnoff warned would supersede the U.S. policy. The USOPC mandate allows for medical and religious exemptions, while Beijing’s will consider medical exemptions but won’t grant any for religious purposes.

Athletes who are granted medical exemptions will have to quarantine in Beijing for 21 days before they can practice for their events.

Finnoff also said he expects that many coronavirus pandemic restrictions and accommodations around Olympic-type sports will linger through at least next summer, especially after slower vaccination rates and the recent spike of infections related to the delta variant tempered optimism that events would return to normal in the lead-up to Beijing.

“We had to totally rethink what are we going to do because this is not a short term,” he said. “We are playing the long game at this point.”