Pope Francis did not preside over the New Year's Eve service in St Peter's Basilica on Friday, although he gave the sermon.
Instead, Cardinal Giovanni Battista Re presided over the thanksgiving vespers with the traditional "Te Deum" hymn of praise.
The pope only wanted to give the sermon, but decided to leave the leadership of the celebration to Cardinal Re, Vatican spokesperson Matteo Bruni said after the mass.
The decision appeared to have been made only shortly beforehand, for reasons that remained unclear.
The pope's chair was moved to beside the altar just minutes before the celebration began, and Pope Francis followed the prayer largely in a seated position.
Francis then went to the pulpit to give the homily and called for a greater show of solidarity and charity during the pandemic.
While many felt as though they were in the same boat during the first phase of the outbreak, later it seemed that many were living by the principle, "save yourself if you can."
The move came a day after Pope Francis cancelled his planned visit to the Christmas nativity scene in St Peter's Square to protect himself and others against the coronavirus as numbers spike worldwide.
The Pope's visit was cancelled to avoid crowds and thus the risk of contracting Covid-19, the Holy See announced on Thursday.
It was not clear whether the pope will celebrate the Eucharist for the Feast of Mary in St Peter's Basilica on New Year's Day.
