Robert F. Kennedy Jr., the health and human services secretary, abruptly canceled a meeting this week of a federal task force that helps determine which preventive health measures must be covered fully by insurance companies, raising concerns about the future of the nonpartisan panel.

The U.S. Preventative Services Task Force had been scheduled to meet Thursday, but its members were informed by email Monday, without explanation, that the meeting would be postponed, according to several participants.

“Moving forward, HHS looks forward to engaging with the task force to promote the health and well-being of the American people,” the notice said.

The agency did not respond to a request for comment.

Created in 1984, the 16-member panel of doctors and other health experts plays a pivotal role in determining whether tens of millions of Americans are eligible for lung cancer screenings, stroke reduction medication and scores of other drugs and preventative services.

Members of the all-volunteer panel are chosen by the health secretary. They meet three times a year in person and also take part remotely in weekly meetings.

The decision to cancel the July meeting follows a Supreme Court ruling last month that upheld the work of the task force — but also affirmed Mr. Kennedy’s authority to disregard its recommendations or to remove members before their terms have expired.