What is the efficacy of standard face masks
DISCLAIMER: This review was produced at speed in the early weeks of the pandemic. It was based on past research on other diseases, and did not include studies in Covid-19. It has been superseded by other, more extensive reviews which do include studies of Covid-19. There are no plans to update this review.To get more news about
surgical mask stock, you can visit tnkme.com official website.
Most real-world research comparing standard face masks with respirator masks has been in the context of influenza or other relatively benign respiratory conditions and based in hospitals. There are no published head-to-head trials of these interventions in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, COVID-19, and no trials in primary or community care settings. Current guidance is therefore based partly on indirect evidence – notably, from past influenza, SARS and MERS outbreaks – as well as expert opinion and custom and practice.
Policy guidance from various bodies (e.g. Public Health England, WHO) emphasises the need to assess the contagion risk of an encounter and use the recommended combination of equipment for that situation. A respirator mask and other highly effective PPE (eye protection, gloves, long-sleeved gown, used with good donning/doffing technique) are needed to protect against small airborne particles in aerosol-generating procedures (AGPs) such as intubation. For non-AGPs, there is no evidence that respirator masks add value over standard masks when both are used with recommended wider PPE measures.
A recent meta-analysis of standard v respirator (N95 or FFP) masks by the Chinese Cochrane Centre included six RCTs with a total of 9171 participants with influenza-like illnesses (including pandemic strains, seasonal influenza A or B viruses and zoonotic viruses such as avian or swine influenza). There were no statistically significant differences in their efficacy in preventing laboratory-confirmed influenza, laboratory-confirmed respiratory viral infections, laboratory-confirmed respiratory infection and influenza-like illness, but respirators appeared to protect against bacterial colonization.
CONTEXT
Concerns have been raised about the limited personal protective equipment (PPE) provided for UK primary and community care staff with some GP surgeries, pharmacies and care homes having very limited provision. We were asked to find out whether and in what circumstances standard masks are putting healthcare workers at risk of contagion compared to respirator masks. A separate review (ongoing) looks at other aspects of PPE.
BACKGROUND
COVID-19 is spread by four means: contact (direct or via a fomite); droplet infection (droplets from the respiratory tract of an infected individual during coughing or sneezing are transmitted onto a mucosal surface or conjunctiva of a susceptible individual or environmental surfaces); airborne (transmission of infectious agents in small airborne particles, particularly during procedures such as intubation); and faeco-oral.1 2 Coughing and sneezing can generate aerosol particles as well as droplets.
This review considers respiratory protective measures e.g. use of face masks as PPE, to reduce droplet and airborne spread. It should be noted that in one recent laboratory study, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, the virus that causes COVID-19) survived airborne as long as SARS COV-1 (the virus that causes SARS) when artificially aerosolised and persisted longer on some surfaces.3 This finding is relevant because it suggests that deposited particulates may become resuspended i.e. airborne, when disturbed.
