Washington DC - The US Food and Drug Administration now led by Health Secretary Robert F. Kennedy Jr. abruptly canceled an annual meeting to update key advisers on newly developed flu vaccines.

Officials confirmed to CBS News on Wednesday that the FDA had unexpectedly and without explanation scrapped its meeting of the Vaccines and Related Biological Products Advisory Committee, which was booked for March 13.

The annual meeting is used to inform key personnel about the year's influenza vaccines, and is a kicking-off point for the manufacturing of next winter's shots.

"We're all left trying to understand what is going on. Why was this meeting canceled? It's an important meeting. What's the plan for flu vaccines this year?" Paul Offit, a member of the FDA advisory committee, told CBS News.

Donald Trump Trump shoots down vital Ukraine demands ahead of Zelensky visit

Offit is also the director of the Vaccine Education Center at the Children's Hospital of Philadelphia and has decades of experience in the field.

He said that after the cancellation, he had received no notice of when or if the meeting would be rescheduled. Any delay, however, could severely limit next year's supply of the vaccine.

"Because the vaccine is grown in eggs, for the most part, it requires six months to produce. So March is six months before September, which is when these vaccines roll out," Offit explained.

RFK Jr. has long cast doubt on the safety and effectiveness of life-saving vaccines, touting thoroughly debunked theories about links to autism.