WHO Recommends Changes to Terminology for Airborne-Transmissible Pathogens

A report released April 18 by the World Health Organization proposes changes to the terminology used to describe pathogens that transmit through the air. The report recommends moving away from terms such as “aerosols” and droplets” in favor of an umbrella term, “infectious respiratory particles” or IRPs, to describe particles of all sizes that contain viral pathogens.

The new terminology would cover pathogens that cause respiratory infections such as COVID-19, influenza, measles, Middle East respiratory syndrome (MERS), severe acute respiratory syndrome (SARS), and tuberculosis. The report recommends using the term “through the air” to describe these and other infectious diseases “where the main mode of transmission involves the pathogen travelling through or being suspended in the air.” Within this mode of transmission, the report proposes “airborne transmission/inhalation” to describe transmission of IRPs expelled into the air and inhaled by another individual and “direct deposition” for transmission following deposit of IRPs on the mouth, nose, or eyes of another person.

Pathogens that spread solely through direct contact between individuals are not covered by the new terminology. Also not covered are pathogens that enter the body through wounds or from needlestick injuries and those such as Legionella that can be harbored in the environment.

The proposed changes reflect consensus among WHO and the leading public health agencies in Africa, China, the European Union, and the United States. Representatives of these organizations agreed that confusion about terminology, particularly related to differences in the ways scientific and professional disciplines described the spread of SARS-CoV-2, may have contributed to confusion about pathogen transmission during the COVID-19 pandemic.

The full report is available from the WHO website. For more information, refer to the organization’s press release.