Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis.

This is a systematic review and meta-analysis to investigate the roles of physical distancing and the use of various types of face masks and eye protection on the transmission of coronaviruses. The title is somewhat misleading as the article pools data from SARS-CoV-1, MERS and SARS-CoV-2 and extrapolates that data to suggest strategies to mitigate the spread of SARS-CoV-2. The description of the methodology is extensive and even mentions the use of Artificial Intelligence to screen and select relevant journals. The latter sounded intriguing, but I was unable to investigate it as a mechanism, either through the paper itself, or via a google search for the company.

As is mostly the case with studies of this type, it found a wide range of heterogeneity in the identified papers studied and then found weak associations between the interventions and the outcomes. In this case, increasing distance, face mask use and higher-grade face mask use were associated with decreased spread of these diseases. The heterogeneity, in this case, was increased by comparing 3 viruses with different R0s and mortality as well as unknown differences in physical characteristics that could alter the airborne stability, droplet size formation etc.  Furthermore, the majority of studies on mask use are really intention to treat studies as proper utilisation is rarely followed up. While this has some validity in a treatment study, in this situation we know that proper mask utilisation is dependent on proper education, comfort of use and perceived benefit/protection. Thus, in present situation, the increased perception of mortality and infectivity of a virus could be expected to markedly change the proper utilisation of masks.

Overall, this paper is useful in condensing the existing knowledge in this area and for helping develop good public health policies. It does not have much importance for anaesthetists as it does not address the specific questions that are important to our profession. Which parts of our work flow are high risk, intubation or extubation? Who are the health care workers most at risk, ENT surgeons during LBOs, anaesthetists dealing with controlled intubations and extubations, or recovery and ICU nurses dealing with coughing and suctioning? Do N95 masks provide sufficient protection in those various high risk situations or is there a need for PAPRs? Due to the widespread nature of this pandemic, compared to SARS-CoV-1 and MERS, hopefully we may have some answers to these questions in the future.

Reviewed by Dr Donald Hannah