The world-famous King's College carol service will be performed in an empty chapel this year.
Usually, the Christmas performance - A Festival of Nine Lessons and Carols - is watched by a rapt congregation and broadcast to millions.
But this year the public will be barred from the hallowed cloisters of the gothic Cambridge chapel.
Dean Stephen Cherry said he was "sorry to disappoint" choral enthusiasts hoping to attend.
But he urged them to enjoy the regular broadcast of the performance on BBC Radio 4 at 15:00 GMT on 24 December.
The college said there would be no congregation this year "as part of the necessary precautions... to ensure that the services are safe".
Instead, it was "looking forward to sharing the joy of its annual Christmas services with the world on radio and television".
A Festival of Nine Lessons and Carols was introduced in 1918 to "bring a more imaginative approach to worship".
It was first broadcast in 1928, and always opens with the carol Once In Royal David's City.
The order of service will be available to download from 18 December.
A Festival of Nine Lessons and Carols will be broadcast live on BBC Radio 4 and the BBC World Service on 24 December and will be repeated at 14:00 on Radio 3 on Christmas Day.