From WHO Guidelines Infection Prevention and Control of Epidemic-and Pandemic-Prone Acute Respiratory Infections (ARI) in Health Care
||Quality of Evidence
||Strength of Recommendation
|Maintain spatial separation (distance of at least 1 m) between each ARI patient and others, including health-care workers (without the use of personal protective equipment [PPE]), to reduce the transmission of ARI.
||Very low to low
From that and other WHO documents the rationale for this recommendation is laid out:
- COVID19 is transmitted between people by droplet transmission from infected people and indirect contact with surfaces in the immediate environment or with objects used on the infected person.
- Droplets are primarily generated from an infected person during coughing, sneezing and talking. Transmission occurs when these droplets are propelled through the air and deposited on the mouth, throat or eyes of another person.
- Most of the volume (> 99%) comprises large droplets that travel short distances (< 1 m) and do not remain suspended in the air.
- Airborne transmission over a greater distance is a possibility in specific circumstances and settings, however these generally relate to medical interventions that would not occur in most other contexts.
The New England Journal of Medicine reported a study in which the COVID-19 virus in aerosol particles were detected in the air for up to 3 hours, however this was achieved under aerosols production conditions which are generally not replicated in the human cough. In more than 75k COVID cases in China, none have been traced to airborne transmission.
On this basis, the WHO recommends droplet and contact precautions similar to the protocols developed for the management of other infectious diseases being: distancing of at least 1metre between patients or between patients and health-care workers.
The WHO acknowledges the limited evidence for its recommendations: “high-quality epidemiological studies are needed to examine the effect of discrete parameters (e.g. 1 m, 2 m) of spatial separation on the reduction of transmission and infection by ARIs.”
Most companies have, in line with the WHO recommendations and with an appropriate abundance of caution, adopted standards of 1.5m or 2m separation in their workplace. Where this cannot be practically be achieved, other safeguards need to be operating including appropriate PPE.