Manila, Feb. 20 -- Pope Francis' health remains serious but not critical as he undergoes treatment for bilateral pneumonia in a Rome hospital, according to a lung specialist who spoke with ANSA on Wednesday.

Pulmonologist Stefano Nardini, former president of the Italian Society of Pneumology, said that the Pope's clinical situation, "based on the information made known, appears serious and to be monitored closely, but not at the moment compromised."

He noted that previous respiratory issues, including the removal of part of a lung at age 21, add complexity to the case.

"The general picture appears complex also, probably, due to the weight of previous events," he said.

"Bilateral pneumonia in an 88-year-old patient is always concerning...