Masks again, again and again.

The Story of mask evidence, barriers, distancing, hygiene, etc.

Physical interventions to interrupt or reduce the spread of respiratory viruses or (A122 for short) is a Cochrane review of the evidence for the effectiveness and harms of all non-pharmaceutical interventions (NPIs) to halt or delay the spread of respiratory viruses. NPIs are also known as physical interventions, excluding drugs, vaccines and other biologics.

The first version of A122 was published in late 2007; the protocol was published a year earlier. Since then, three updates were published, and the last one (with updated searches to January 2020) was published in November 2020. The BMJ also published two updates.

 The current update has been accepted for publication and is undergoing copy editing, and its conclusion will be the topic of a further post, once published.

The first three versions of A122 included evidence from randomised and non-randomised comparative studies on a range of interventions such as personal hygiene, distancing and barriers (gloves, masks, goggles, antisept…