Pope Francis is sitting upright and continuing to receive treatment for double pneumonia, more than a week after he was admitted to a hospital in Rome. The Vatican said the pope had a peaceful night and was sitting in his armchair on Wednesday receiving therapy.

Pope Francis is being treated in hospital for double pneumonia — but what is this condition, and why might the pope be particularly vulnerable to it?

What does Pope Francis having "double pneumonia" mean? What should you look for in the elderly? How can you avoid getting pneumonia?