"Every day we witness the testimony of courage and sacrifice of health care workers, and nurses in particular, who, with professionalism, self-sacrifice and a sense of responsibility and love for neighbor, assist people affected by the virus, even to the point of putting their own health at risk," the Pope said in a message marking the May 12 celebration of International Nurses Day and the 200th anniversary of the birth of Florence Nightingale.

"Thank you for your service to humanity," the Pope wrote.

Photo Gallery: Nurses at Work Around the World

Pope Francis also paid tribute to the nurses who contracted the virus and died, assuring their families that "the Lord knows each of them by name."

"In many countries," he said, "the pandemic has also brought to light a number of deficiencies in the provision of health care," including the need to invest in nurses and give them greater respect and recognition.

Pope Francis used his message to nurses to also "ask leaders of nations throughout the world to invest in health care as the primary common good, by strengthening its systems and employing greater numbers of nurses, so as to ensure adequate care to everyone with respect for the dignity of each person."

Nurses and midwives, he said, have a "very special vocation" of being "guardians and preservers of life."

"You are an image of the Church as a 'field hospital' that continues to carry out the mission of Jesus Christ, who drew near to and healed people with all kinds of sickness and who stooped down to wash the feet of his disciples," Pope Francis said.

Nurses and midwives know that they need scientific and technical knowledge to help their patients, but that their vocation means also bringing "human and humanizing" qualities to their patient interactions.

"Taking care of women and men, of children and elderly, in every phase of their life from birth to death," he said, "you are tasked with continuous listening aimed at understanding what the needs of that patient are in the phase that he or she is experiencing."

"Before the uniqueness of each situation, indeed, it is never enough to follow a protocol, but a constant – and tiresome! – effort of discernment and attention to the individual person is required," Pope Francis wrote.

"I would like to say a special word to midwives who assist women in their pregnancies and help them give birth to their children," he wrote. "Your work is among the most noble of professions, for it is directly dedicated to the service of life and of motherhood."