Pope Francis, suffering a flare-up of a sciatica condition that causes pain in his right leg, missed a New Year's Eve service on Thursday and will also not preside at a New Year's Day Mass.
It was believed to be the first time since he became pope in 2013 that Francis, who turned 84 this month, has been prevented by health reasons from leading a major papal event.
The year-end vespers service that the pope was to have led was said by Cardinal Giovanni Battista Re, and the Friday Mass, marking the Catholic Church's World Day of Peace, will be said by Cardinal Pietro Parolin, the Vatican secretary of state.
Both the vespers and the Mass require the main celebrant to stand for most of the service.
At the vespers, Re read a sermon the pope had prepared, giving thanks for the kindness people have shown others in dealing with the coronavirus pandemic.
The pope is still scheduled to read his noon address and prayer on Friday as planned, the Vatican said in a statement earlier on Thursday when it announced the change.
Because of coronavirus restrictions in Italy, both the vespers and Mass are being held from a secondary altar in St. Peter's Basilica with only about 200 people instead of the 10,000 the basilica holds.
Francis suffers from sciatica, a condition that causes pain that radiates from the lower back along the sciatic nerve to the lower part of the body.
He is sometimes seen walking with difficulty because of the pain and receives regular physical therapy because of the condition.
In March this year, a bad cold kept him from taking part in a week-long Lenten retreat with his senior aides south of Rome.
In 2014, a year after he was elected pope, Francis was forced to cancel several engagements because of what was believed to be a stomach ailment. That year he also missed walking in a Lenten procession because of leg pain.
But his health has been generally good since his election.
Last week, he presided at a Christmas Eve Mass and the next day read a Christmas Day "Urbi et Orbi" (to the city and the world) message while standing, both without apparent difficulties.
His latest appearance was at Wednesday's general audience, held virtually in the Vatican because of the pandemic. There too, he showed no apparent difficulties, although he sits at the audiences.
