Is pneumonia (infection of the lungs) contagious?

From the Guidelines

Pneumonia can be contagious, but it depends on the cause, with bacterial and viral pneumonia being contagious and spread through respiratory droplets when an infected person coughs, sneezes, or talks, as supported by the most recent study in 2021 1. The contagious types of pneumonia include pneumococcal pneumonia, influenza pneumonia, and COVID-19 pneumonia. However, not all pneumonia is contagious, with fungal pneumonia, aspiration pneumonia, and chemical pneumonia being non-contagious. Some key points to consider:

• The contagious period for pneumonia typically lasts from when symptoms first appear until 24-48 hours after starting effective antibiotic treatment for bacterial pneumonia, or 5-7 days after symptom onset for viral pneumonia.
• To prevent transmission, it is essential to practice good hand hygiene, cover coughs and sneezes, wear masks when sick, and maintain distance from others when infected.
• Those with weakened immune systems, the elderly, and young children are at higher risk for contracting pneumonia from contagious individuals, as noted in a study from 2018 2.
• The American Thoracic Society and Infectious Diseases Society of America have updated guidelines to help streamline disease management, emphasizing the use of timely, appropriate, and adequate antibiotic coverage to decrease mortality and avoid drug resistance, as mentioned in a study from 2020 3.
• Novel antibiotics have been studied for community-acquired pneumonia (CAP) and extend the choice of therapy, particularly for those who are intolerant of, or not responding to standard treatment, including those who harbor drug-resistant pathogens, as discussed in a study from 2021 1.

From the Research

Pneumonia Contagiousness

• Pneumonia is a common acute respiratory infection that affects the alveoli and distal airways, and it is a major health problem worldwide 4.
• The disease can be caused by a large variety of microorganisms, including bacteria, respiratory viruses, and fungi, which can be contagious 4, 5.
• Community-acquired pneumonia can be spread through respiratory droplets, contact with contaminated surfaces, or close contact with an infected person 5.
• Hospital-acquired pneumonia can be spread through healthcare workers, contaminated medical equipment, or the hospital environment 5.
• The risk of transmission depends on various factors, including the type of microorganism, the severity of the disease, and the effectiveness of infection control measures 4, 5.

Transmission Factors

• The host immune response plays a crucial role in the development of pneumonia, and individuals with weakened immune systems are more susceptible to infection 4.
• Pathogen characteristics, such as virulence and antimicrobial resistance, can also affect the transmission of pneumonia 5, 6.
• Geographical variations in the prevalence of microorganisms can influence the risk of transmission, and certain regions may have a higher incidence of specific types of pneumonia 4, 5.

Prevention and Control

• Effective infection control measures, such as hand hygiene, respiratory isolation, and vaccination, can help prevent the transmission of pneumonia 4, 5.
• Antimicrobial therapy, such as antibiotics, can be used to treat pneumonia, but the overuse and misuse of these agents can contribute to antimicrobial resistance 7, 6, 8.
• New antibiotic and non-antibiotic therapies, as well as rapid and accurate diagnostic tests, are being developed to improve the management of pneumonia and reduce the risk of transmission 4.