The Vatican press office released a photo of Pope Francis concelebrating Mass on Sunday in a private chapel of Rome's Gemelli Hospital, where he continues to receive treatment.

March 13 (UPI) -- Pope Francis marked the 12th year of his pontificate Thursday while still recovering from lung infection. The anniversary is a public holiday at the Vatican but no events were planned to celebrate the occasion. Francis' condition was described as "stationary" Wednesday as the Vatican said he had been improving.

The photo is said to have been taken Sunday when Francis was co-celebrating Mass in the chapel of his hospital suite where he has been battling a health crisis.