Internationally, there are conflicting recommendations regarding the use of facemasks 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 facemasks 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 facemasks 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 facemasks 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 facemasks 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 facemasks for primary prevention of respiratory illness. Effect estimates vary based on study design and exposure setting. Across three randomised trials, wearing a facemask 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 facemasks 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 facemasks for preventing COVID-19 infections. However, they do not provide evidence of the actual effects of facemask 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.
Despite taking into consideration the seriousness of the threat (59% of all registered COVID-19 related deaths in Norway has occurred in nursing homes), in the current epidemiological situation there is little scientific evidence to support recommending that healthcare personnel in nursing homes wear facemasks for primary prevention (when no cases were yet been identified) of COVID-19. If the epidemiological situation worsens substantially in the general population in a particular geographical area or in nearby nursing homes, one may reconsider the recommendation as a precautionary measure despite the lack of evidence.
If facemasks are to be worn for primary prevention in a worsened epidemiological situation, only quality-controlled medical facemasks can be recommended. National priorities for the use of personal protective equipment may apply given existing shortages. This has not been taken into consideration in this review.
Evidence of the effects of non-medical facemasks is still less certain than for medical facemasks, but they are likely to be less effective. We do not recommend the use of non-medical facemasks for primary prevention of COVID-19 in nursing homes. Respirators (N95, FFP2 or FFP3) are intended for protecting the user in high-risk settings. They have no role in primary prevention and should not be used for this purpose.