J09-J18: Influenza and pneumonia

Influenza and pneumonia are two related respiratory illnesses that are primarily spread via tiny droplets released when an infected person coughs or sneezes. Influenza, also known as the flu, often begins with symptoms like fever, chills, muscle aches, cough, and fatigue. It can weaken the immune system, leaving the body more susceptible to other infections such as pneumonia. Pneumonia refers to an infection where one or both lungs become inflamed, often filled with fluid or pus. It can be caused by various organisms, including bacteria, viruses and fungi. Pneumonia symptoms, which can range from mild to severe, often include chest pain, cough with phlegm, fatigue, fever, and shortness of breath. Both these infections can progress quickly in high-risk individuals such as children, the elderly and those with weakened immune systems or underlying health conditions.