Policy makers must act on incomplete evidence in responding to COVID‐19

Type Journal Article Author Karla Soares‐Weiser Author Toby Lasserson Author Karsten Juhl Jorgensen Author Steven Woloshin Author Lisa Bero Author Michael D. Brown Author Baruch Fischhoff URL https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.ED000149/full Issue 11 Publication Cochrane Database of Systematic Reviews ISSN 1465-1858 Date 20/11/2020 Extra Publisher: John Wiley & Sons, Ltd DOI 10.1002/14651858.ED000149 Library Catalog www.cochranelibrary.com Language en Abstract Reducing the transmission of Coronavirus disease 2019 (COVID‐19) is a global priority. Toward this end, public health officials and politicians across the world have been seeking scientific expertise to guide policy. In response, investigators have rushed to share new results on preprint servers, and journals have expedited editorial and peer review processes to publish them. The urgency to define the relevant knowledge base in preventing, diagnosing, and managing COVID‐19 infection and its sequelae has required intense collaboration in evidence generation and synthesis, in order to provide public health officials with authoritative guidance. Cochrane has responded to the crisis by gathering its community, working closely with the World Health Organization (WHO) and other stakeholders, in developing and publishing several systematic reviews on the effectiveness of behavioural public health measures for reducing COVID‐19 infection.[1] These measures include masks, handwashing, physical distancing, quarantine, contact tracing, screening, and travel restrictions. Because COVID‐19 is still so new, however, these reviews have largely summarized effects on transmission of other viruses in non‐pandemic conditions. The conclusions of these reviews are similar. None has found robust, high‐quality evidence for any behavioural measure or policy. Each has identified important limitations to their respective bodies of evidence. An updated review of physical interventions by Jefferson and colleagues assesses three commonly recommended interventions: masks, hand hygiene, and physical distancing.[2] They found evidence that masks had limited or no benefit in terms of preventing influenza‐like illnesses or laboratory‐confirmed influenza. However, except for a handful of studies, most of the evidence is from studies examining effects in wearers. An important effect may still lie in how masks reduce transmission of virus to others, which is more difficult to ascertain.[3] Resulting uncertainty in the evidence for public health measures has fed controversies regarding the legitimacy of public health policies involving these measures, with face masks being a special target for criticism.[4, 5]