Infectious respiratory particles or IRPs

Pathogens that transmit through the air will be described by the term ’infectious respiratory particles’ or IRPs, according to the World Health Organization (WHO).

• Need: There was a lack of a common terminology to describe the transmission of these pathogens, which was particularly challenging during the global COVID-19 pandemic.
• Varying terminologies highlighted gaps in common understanding and contributed to challenges in public communication and efforts to curb the transmission of the pathogen.
• 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, and these particles should be described with the term IRPs.
• IRPs exist on a continuous spectrum of sizes, and no single cut-off points should be applied to distinguish smaller from larger particles.
• Under the umbrella of ‘through the air transmission’, two descriptors can be used:
  • Airborne transmission or inhalation, for cases when IRPs are expelled into the air and inhaled by another person.
  • Direct deposition, for cases when IRPs are expelled into the air from an infectious person, and are then directly deposited on the exposed mouth, nose or eyes of another person nearby, then entering the human respiratory system and potentially causing infection.