<s>[INST] Pneumonia Causes [/INST] Pneumonia infection can be caused by bacteria, viruses, fungi, or chemical and physical injury. It is a lung inflammation that most often follows bacterial or viral respiratory infections. Frequent causes include the common cold (e.g. rhinovirus infection), Influenza (flu), COVID-19, pneumococcal disease or respiratory syncytial viral (RSV) infection.

In pneumonia, the alveoli (air-filled sacs in the lungs responsible for absorbing oxygen) are filled with pus and other fluids making it difficult for oxygen to reach the blood. With little oxygen in the blood, your body cells cannot function properly. When the lungs become congested with fluids, breathing becomes difficult. Source: Health Hub SG. Link: https://www.healthhub.sg/a-z/diseases-and-conditions/topic_pneumonia. Field: Lung Disease. Disease: Pneumonia </s>