Triaging of Respiratory Protective Equipment on the assumed risk of SARS-CoV-2 aerosol exposure in patient-facing healthcare workers delivering secondary care: a rapid review

BACKGROUNDO_ST_ABSObjectivesC_ST_ABS"In patient-facing healthcare workers delivering secondary care, what is the evidence behind UK Government PPE Guidance on surgical masks versus respirators for SARS-CoV-2 protection?" METHODSTwo independent reviewers searched MEDLINE, Google Scholar and grey literature 11th - 30th April 2020. Studies published on any date containing primary data comparing surgical facemasks and respirators specific to SARS-CoV-2, and studies underpinning government PPE guidance, were included. Appraisal was performed using CASP checklists. Results were synthesised by comparison of findings and appraisals. RESULTSIn all three laboratory studies of 14 different respirators and 12 surgical facemasks, respirators were significantly more effective than facemasks in protection factors, reduction factors, filter penetrations, and total inspiratory leakages at differing particle sizes, mean inspiratory flows, and breathing rates. Tests included live viruses and inert particles on dummies and humans. In six clinical studies, 6,502 participants, there was no consistent definition of "exposure" to determine the efficacy of RPE. It is difficult to define "safe". The only statistically significant result found continuous use of respirators more effective in clinical respiratory illness compared to targeted use or surgical facemask. CONCLUSIONSThere is a paucity of evidence on the comparison of FRSMs and respirators specific to SARS-CoV-2, and poor-quality evidence in other contexts. Indirectness results in extrapolation of non-SARS-CoV-2 specific data to guide UK Government PPE guidance. The appropriateness of this is unknown given the uncertainty over the transmission of SARS-CoV-2. O_LIThe evidence base for UK Government PPE guidelines is not based on SARS-CoV-2 and requires generalisation from low-quality evidence of other pathogens/particles. C_LIO_LIThere is a paucity of high-quality evidence regarding the efficacy of RPE specific to SARS-CoV-2. C_LIO_LIHMGs PPE guidelines are underpinned by the assumption of droplet transmission of SARS-CoV-2. C_LI Triaging the use of FFP3 respirators might increase the risk of COVID-19 faced by some. FUNDINGThis review was unfunded and unsponsored. ARTICLE SUMMARYO_ST_ABSStrengths and limitations of this studyC_ST_ABSStrengthsO_LIThis article does not aim to prove an intervention as more effective than a comparator. It identifies a paucity of evidence on respiratory protective equipment specific to SARS-CoV-2. C_LIO_LIThe results of this study will allow for future study with a real and tangible effect towards the wellbeing of healthcare workers nationwide, and perhaps internationally. C_LIO_LIThis article has an exceptionally broad range- from infection control, to public health, to biomechanical engineering, to industry. Its extensive reach would allow for citations from several disciplines. C_LI LimitationsO_LIThis study reviews evidence specific to a novel virus. Naturally, there is a paucity of specific evidence. C_LI