How to address SARS-CoV-2 airborne transmission to ensure effective protection of healthcare workers? A review of the literature - 05/08/21
on behalf of the
Scientific Committee of the French Society for Hospital Hygiene
Highlights |
• | Various definitions of airborne-related terminology have generated confusion. An aerosol can contain both liquid (droplets) and solid (droplet nuclei) particles of various sizes. |
• | Respiratory activities produce aerosols containing a wide spectrum of particles in highly variable sizes and loads. Differentiation of “droplets” from “air” transmission fails to reflect the complexity of respiratory pathogen transmission. |
• | Environmental factors condition the risk of transmission of the pathogens present in aerosols, which are not transposable between one another. Small particles of matter serve as a vector for SARS-CoV-2 virions and facilitate their spread and/or introduction in the lower airways. |
• | Molecular detection of SARS-CoV-2 in environmental samples should amplify 2 or 3 targets, in the same manner as biologic samples. Results should be interpreted carefully as long as no active replication has occurred in the environment. |
• | SARS-CoV-2 infectiousness from environmental samples in healthcare settings (excluding experimental contexts) has yet to be demonstrated. |
• | Current scientific evidence suggests that surgical and N95/FFP2 masks confer equivalent protection against airborne viral infections to HCWs engaged in routine care. Although SARS-CoV-2 virion is a nanoparticle, it is usually carried by larger particles, which are easily stopped and contained by a mask. |
• | Airborne transmission seems to occur under specific circumstances with high viral density, which is more common in community than in healthcare facilities. |
• | While airborne transmission is possible, the major route of transmission in healthcare settings is droplet-mediated. |
Abstract |
SARS-CoV-2 mainly infects the respiratory tract, and presents significantly higher active replication in the upper airways. To remain viable and infectious, the SARS-CoV-2 virion must be complete and integral, which is not easily demonstrated in the environment by positive reverse transcriptase PCR results. Real-life conditions in healthcare settings may be conducive to SARS-CoV-2 RNA dissemination in the environment but without evidence of its viability and infectiveness in air. Theoretically, SARS-CoV-2 shedding and dissemination nonetheless appears to be air-mediated, and a distinction between “air” and “droplet” transmission is too schematic to reflect the reality of the respiratory particles emitted by patients, between which a continuum exists. Airborne transmission is influenced by numerous environmental conditions that are not transposable between different viral agents and situations in healthcare settings or in the community. Even though international guidelines on “droplet” versus “air” precautions and personal protective equipment (surgical versus respirator masks) are under discussion, the existing literature underscores the effectiveness of “droplet” precautions as a means of protecting healthcare workers. Differentiation in guidelines between healthcare venues, community settings and, more generally, confined environments is of paramount importance, especially insofar as it underlines the abiding pandemic-related need for systematic mask wearing by the general population.
Le texte complet de cet article est disponible en PDF.Keywords : COVID-19, Infection control, Pandemic, Aerosol, Mask
Plan
Vol 51 - N° 5
P. 410-417 - août 2021 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.