The Vatican on Sunday released the first photograph of Pope Francis in more than a month, showing the pontiff in a three-quarter view from behind wearing a purple stole typical of Lenten liturgical vestments and sitting in a wheelchair before the altar of his personal hospital chapel. The Vatican said he was participating in the celebration of the Mass with other priests in the 10th-floor papal apartment in the Gemelli hospital. No one else is visible in the photo and it is the first mention the Vatican has made of the pope’s participation in celebrating Mass since his Feb. 14 hospitalization for a bout with chronic bronchitis that quickly turned into double pneumonia. There was no obvious sign that he was receiving supplemental oxygen mentioned in medical bulletins. Doctors this week said the pontiff was no longer in critical, life-threatening condition, but they have continued to emphasize that his condition remained complex due to his age, lack of mobility and the loss of part of a lung as a young man. In an audio recording released March 6, the pope spoke in a feeble and labored voice as he thanked the faithful in St. Peter’s Square for their prayers. His condition has been gradually improving over the last week, leading the Vatican to suspend morning updates and to issue less frequent medical bulletins. An X-ray this week confirmed that the infection was clearing. In the most recent bulletin on Saturday, doctors said they were working to reduce the pope’s reliance on a non-invasive ventilation mask at night, which will allow his lungs to work more. He was continuing to receive high-flow supplemental oxygen, delivered by a nasal tube, during the day — although no such apparatus was evident in the photograph. ‘Pope of the children’ Earlier Sunday, dozens of children — many from war-torn countries, and toting yellow and white balloons — gathered outside Rome’s Gemelli hospital to greet Francis on his fifth Sunday hospitalized. While the pope did not appear from the 10th-floor suite of windows, he thanked them and acknowledged their presence in the traditional Sunday blessing. “I know that many children are praying for me; some of them came here today to Gemelli as a sign of closeness,’’ the pontiff said in the Angelus text prepared for the traditional prayer but not delivered live again. “Thank you, dearest children! The pope loves you and is always waiting to meet you,’’ Francis said. The Rev. Enzo Fortunato, president of the pontifical committee for World Children's Day who organized the event, said that the gathering of children with their parents was a form of spiritual medicine for the 88-year-old pontiff. He called it "the most beautiful caress.’’ “The children represent a symbolic medicine for Pope Francis,’’ Fortunato said. "Letting him know that so many children are here for him cheers the heart.’’ A small group of children, whose balloons represented the colors of the Vatican flag, briefly entered the hospital to leave behind their drawings, messages and flowers for Francis. Many of the children came from poorer Italian districts or from countries impacted by war, some having arrived in Italy from Afghanistan and Syria via humanitarian corridors set up by the Sant’Egidio charity in agreement with the Italian government; others were from Ukraine, Gaza, South America and Africa. One of them was 12-year-old Anastasia, who got up at 5 a.m. to make the trip from Naples with the hopes of delivering the message directly to the pope. “I wrote, ‘Pope Francis, get well and return home soon,’” she said. "We love you, all of the children are praying for you.’' Andrea Iacomini, the spokesman for UNICEF in Italy, said besides demonstrating affection for the pope, the group also wanted to say "enough'' to conflicts that are impacting 500 million children in 59 countries. "This pope is not just a religious leader, he is a great global leader. A man of peace. This pope is pope of the children.'' Iacomini said. Not seen publicly since being admitted to hospital Francis typically delivers the Angelus from a window overlooking St. Peter’s Square to the gathered faithful, who have grown more numerous due to the Jubilee year that Francis inaugurated in December. In the written text, Francis said he was thinking of others, who like him, are in a fragile state. “Our bodies are weak, but even like this, nothing can prevent us from loving, praying, giving ourselves, being for each other, in faith, shining signs of hope,’’ the pope said. Along with a stop at St. Peter’s to seek indulgences by walking through the basilica’s Holy Door, pilgrims are now also adding a stop at Gemelli, a 15-minute train ride from the Vatican. Francis has not been seen publicly since he was admitted to the hospital after a bout of bronchitis that made it difficult for him to speak. Doctors soon added a diagnosis of double pneumonia and a polymicrobial (bacterial, viral and fungal) infection.