Pneumonia

Pneumonia is an infection of the lungs — caused by bacteria, viruses, or fungi — that inflames the air sacs and can fill them with fluid or pus, leading to cough, fever, chills, and difficulty breathing. It ranges from mild to life-threatening and is among the most common causes of hospitalization and death in the United States. Pneumonia results in approximately 1.2 million emergency department visits annually and was responsible for 41,627 deaths in 2024, or 12.2 per 100,000 population. Despite this ongoing toll, significant progress has been made — age-adjusted pneumonia mortality declined from 22.9 to 9.9 per 100,000 between 1999 and 2023, with males consistently experiencing higher mortality than females. Those at greatest risk include adults over 65, young children, and individuals with chronic conditions or weakened immune systems. Vaccination remains a primary prevention tool, yet only 25.1% of U.S. adults had ever received a pneumococcal vaccine as of 2024 — a concerning gap given the availability of highly effective vaccines. Community-acquired pneumonia (CAP) is the most common form, while hospital-acquired and ventilator-associated pneumonia carry significantly higher mortality rates. Treatment depends on the causative pathogen and may include antibiotics, antivirals, supportive care, or hospitalization.