From the Guidelines
Pneumonia is primarily spread through respiratory droplets when an infected person coughs, sneezes, or talks, as well as through contact with contaminated surfaces and infected individuals. These droplets containing bacteria, viruses, or fungi can be inhaled directly by others nearby or can land on surfaces where they may remain viable for hours 1. When someone touches these contaminated surfaces and then touches their eyes, nose, or mouth, they can become infected. Close contact with infected individuals increases transmission risk, especially in crowded settings with poor ventilation. Some types of pneumonia are more contagious than others, with viral and bacterial pneumonia being generally more transmissible than fungal pneumonia.
The spread of pneumonia can be reduced by practicing good hand hygiene, covering coughs and sneezes, wearing masks when ill, maintaining distance from sick individuals, and ensuring adequate ventilation in indoor spaces 2. Vaccination against common pneumonia-causing pathogens like pneumococcus and influenza can also prevent transmission by reducing the number of infected individuals in a community. According to the most recent study, the main route of transmission is respiratory droplet transmission, and it can also be transmitted through contact 1.
Key factors that increase the risk of transmission include:
- Close proximity to infected individuals
- Poor ventilation in indoor spaces
- Inadequate hand hygiene
- Not covering coughs and sneezes
- Not wearing masks when ill
- Inadequate vaccination against common pneumonia-causing pathogens It is essential to note that the severity of pneumonia transmission can vary broadly, and some forms, such as those caused by Legionella or Mycobacterium tuberculosis, can be particularly severe and even fatal 3. Therefore, it is crucial to take preventive measures to reduce the risk of transmission and to seek medical attention immediately if symptoms of pneumonia occur.
From the Research
Modes of Transmission of Pneumonia
The mode of transmission of pneumonia can be understood through various studies, including those on COVID-19 and other respiratory viruses. Key points to consider include:
- Respiratory viruses, including those causing pneumonia, can be transmitted via four major modes: direct (physical) contact, indirect contact (fomite), (large) droplets, and (fine) aerosols 4.
- For COVID-19, specifically, the virus is thought to spread mainly from person-to-person through respiratory droplets produced when an infected person coughs, sneezes, or talks 5, 6.
- The transmission of pneumonia-causing pathogens can also occur through aerosols formed during surgical and dental procedures, as well as through other body fluids and secretions 6.
- Indirect transmission may occur via fomites or surfaces present within the immediate environment of an infected patient, and objects used on the infected person 6.
Understanding Transmission Dynamics
To effectively prevent the spread of pneumonia, it's crucial to understand the relative contribution of different modes of transmission. This includes:
- Recognizing that the probability of direct infection of the acinar airways due to inhalation of particles emitted by a bystander cough is very low 5.
- Acknowledging that COVID-19 pneumonia must often be preceded by SARS-CoV-2 infection of the upper airways, suggesting that interventions targeting the upper airways could be effective in preventing pneumonia 5.
- Considering that non-pharmaceutical interventions, such as disinfection of the throat and nasal and oral mucosa, may effectively keep the viral load of the upper airways low enough to avoid or prolong the progression of the disease 5.