Should healthcare personnel in nursing homes without respiratory symptoms wear facemasks for primary prevention of COVID-19? A rapid review

Internationally, there are conflicting recommendations regarding the use of face-masks by asymptomatic personnel in long-term care facilities for primary prevention (when no cases have yet been identified) of COVID-19 infection.

Nursing home residents are particularly vulnerable to serious COVID-19. Up until 10 May 2020, 138 COVID-19 related deaths have been reported in nursing homes and other healthcare facilities other than hospitals, accounting for 59% of all COVID-19 related deaths in Norway. However, there have been relatively few notifications of COVID-19 outbreaks in nursing homes in Norway, and the number of outbreaks appear to have declined since week 14 without the use of face-masks by healthcare personnel for primary prevention.

An Evidence to Decision (EtD) framework was used to guide the process from reviewing the evidence to a recommendation. An evidence base was made by a structured literature review using the L·OVE COVID-19 database and a living COVID-19 evidence map as data sources. Relevant ongoing reviews and studies were searched for in PROSPERO, the list of COVID-19 trials in the International Clinical Trials Registry Platform (ICTRP) (updated 12 May 2020) and ClinicalTrials.gov COVID-19 list. Additional articles were identified by checking the references in retrieved articles and personal contacts.

There is no direct evidence of the effects of healthcare personnel in nursing homes wearing face-masks for primary prevention (when no cases have yet been identified) of COVID-19 and no directly relevant trials are currently registered in the International Clinical Trials Registry Platform (ICTRP) or ClinicalTrials.gov. There is limited evidence of the effect of widespread use of face-masks in community settings on COVID-19 infection rates. This evidence comes from observational studies on group level which have a high risk of bias.

A systematic review of face-masks and similar barriers to prevent respiratory illness such as COVID-19 did not find any studies in nursing homes or other long-term care facilities.

There is substantial variation in the study populations, the interventions, the outcome measures, the study designs, and the estimated effects of wearing face-masks for primary prevention of respiratory illness. Effect estimates vary based on study design and exposure setting. Across three randomised trials, wearing a face-mask reduced the odds of developing influenza-like illness/respiratory symptoms by around 6% (OR 0.94, 95% CI 0.75 to 1.19, I2 29%, low certainty evidence).

Evidence from laboratory filtration studies suggests that non-medical face-masks may reduce the transmission of larger respiratory droplets. There is little evidence regarding transmission of small aerosolized particulates of the size potentially exhaled by asymptomatic or presymptomatic individuals with COVID-19. Key findings of relevant laboratory studies provide some information about the potential effectiveness of face-masks for preventing COVID-19 infections. However, they do not provide evidence of the actual effects of face-mask use.

An expert panel discussed and assessed the background and evidence using a defined set of criteria. The assessments for each criterion were judged in a consensus process and the overall recommendation and report were reviewed by the panel.