Objectives
The aim of this overview of reviews is to produce an up-to-date evidence map of systematic reviews (SRs) on the effects – both, intended and unintended – of NPIs that were applied to limit the spread of SARS-CoV-2. The evidence map should enable production of rapid evidence summaries to support decision makers, contribute to a retrospective assessment of the appropriateness of NPIs and identify evidence gaps.
Methods
We performed systematic literature searches in the COVID L.OVE repository. Title and abstract screening was performed independently by two reviewers, full-text screening was performed by one reviewer and checked by another. We used AMSTAR 2 for quality assessment of selected SRs.
Results
The first round of literature searches was performed on 10 March 2022 and yielded 1724 hits. During title and abstract screening, we categorised publications according to studied NPIs and outcomes to enable a stepwise full-text screening. Of the 324 potentially relevant publications, we first screened those that investigated masks and effectiveness outcomes in full-text and included 26 SRs. We selected 7 SRs for evidence summary based on recency and study overlap (i.e., SRs that included at least 2 primary studies that are not included in a more recent SR). All SRs were rated critically low quality by AMSTAR 2 assessment. All SRs reported an association between mask wearing and reduced transmission of SARS-CoV-2, but certainty of evidence was mostly deemed low. Evidence for the effect of mask wearing on mortality is sparse. Full-text screening is still ongoing and evidence summaries for other NPIs, as well as for unintended effects will be produced.
Conclusions
The most recent and comprehensive SRs on mask wearing all report reduced transmission of SARS-CoV-2 but certainty of evidence is deemed low. Quality of the SRs was deemed critically low by AMSTAR 2 assessment.