On April 18, the World Health Organization (WHO) published a global technical consultation report announcing updated terminology for pathogens that transmit through the air. The pathogens covered include those that cause respiratory infections, e.g. COVID-19, influenza, measles, Middle East respiratory syndrome (MERS), severe acute respiratory syndrome (SARS), and tuberculosis, among others.
A press release on the announcement says that “The publication, entitled ‘Global technical consultation report on proposed terminology for pathogens that transmit through the air,’ is the result of an extensive, multi-year, collaborative effort and reflects shared agreement on terminology between WHO, experts and four major public health agencies: Africa Centres for Disease Control and Prevention; Chinese Center for Disease Control and Prevention; European Centre for Disease Prevention and Control; and United States Centers for Disease Control and Prevention. This agreement underlines the collective commitment of public health agencies to move forward together on this matter.”
Further, “The wide-ranging consultation was conducted in multiple steps in 2021-2023 and addressed a lack of common terminology to describe the transmission of pathogens through the air across scientific disciplines. The challenge became particularly evident during the COVID-19 pandemic as experts from various sectors were required to provide scientific and policy guidance. Varying terminologies highlighted gaps in common understanding and contributed to challenges in public communication and efforts to curb the transmission of the pathogen.”
The following common descriptions are now being used to characterize the transmission of pathogens through the air, under typical circumstances:
- Individuals infected with a respiratory pathogen can generate and expel infectious particles containing the pathogen, through their mouth or nose by breathing, talking, singing, spitting, coughing or sneezing—these particles should be described with the term “infectious respiratory particles” (IRPs)
- IRPs exist on a continuous spectrum of sizes, and no single cutoff points should be applied to distinguish smaller from larger particles—this facilitates moving away from the dichotomy of previously used terms: ‘aerosols’ (generally smaller particles) and ‘droplets’ (generally larger particles)
Under the umbrella of ‘through the air transmission’, two descriptors can be used:
- Airborne transmission or inhalation
- Direct deposition
