A lung infection, often referred to as pneumonia, occurs when harmful germs, such as bacteria or viruses, invade the lungs. This can lead to inflammation and fluid buildup in the air sacs, making it difficult to breathe. Symptoms may include cough, fever, chest pain, and difficulty breathing. Lung infections can affect anyone but are more common in young children, the elderly, and individuals with weakened immune systems. Treatment typically involves antibiotics for bacterial infections and supportive care for viral infections. Vaccines, such as the pneumococcal vaccine, can help prevent certain types of lung infections.