Surgical masks, N95 respirators, Hand Hygiene – whats best to interrupt or reduce the spread of respiratory viruses

Physical interventions to interrupt or reduce the spread of respiratory viruses – Cochrane Review



Viral epidemics or pandemics of acute respiratory infections (ARIs) pose a global threat. Examples are influenza (H1N1) in  2009, severe acute respiratory syndrome (SARS) in 2003, and coronavirus disease 2019 (COVID‐19).

Antiviral drugs and vaccines are expensive and may be insufficient to prevent their spread. 


Assess the effectiveness of physical interventions to interrupt or reduce the spread of acute respiratory viruses.


 78 relevant studies were identified from low, middle and high‐income countries worldwide: in hospitals, schools, homes, offices, childcare centres, and communities during non‐epidemic influenza periods, the global H1N1 influenza pandemic in 2009, epidemic influenza seasons up to 2016, and during the COVID‐19 pandemic.

Five trials were funded by government and pharmaceutical companies, and nine trials were funded by pharmaceutical companies.

No studies looked at face shields, gowns and gloves, or screening people when they entered a country.


There is uncertainty about the effects of face masks. The low to moderate certainty of evidence means our confidence in the effect estimate is limited. The pooled results of RCTs did not show a clear reduction in respiratory viral infection with the use of medical/surgical masks. There were no clear differences between the use of medical/surgical masks compared with N95/P2 respirators in healthcare workers when used in routine care to reduce respiratory viral infection.

Hand hygiene is likely to modestly reduce the burden of respiratory illness – influenza-like illness and laboratory-confirmed influenza.

Harms associated with physical interventions were under‐investigated.

There are a number of limitations that this Cochrane Review has listed

The full text of the review is available at this LINK

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