Several personal protective and social measures, including handwashing, mask wearing, and physical distancing are associated with reductions in the incidence covid-19 and should be continued alongside vaccination, suggest experts after reviewing the latest evidence in The BMJ today.
However, they say more stringent measures, such as lockdowns and closures of borders, schools, and workplaces need further assessment to weigh their potential negative effects on general populations.
Public health (or non-pharmaceutical) interventions are known to be beneficial in fighting respiratory infections like influenza, and countries around the world are implementing various public health measures to curb the spread of SARS-CoV-2.
Yet, previous reviews have not been robust enough to allow researchers to make firm conclusions about the effectiveness of such measures in reducing covid-19 incidence rates.
To plug this knowledge gap, the researchers trawled databases for studies that assessed the effectiveness of public health measures in reducing the incidence of covid-19, SARS-CoV-2 transmission, and covid-19 mortality.
In all, 72 studies met their inclusion criteria, of which 35 evaluated individual public health measures and 37 assessed multiple public health measures.
Of the 35 studies of individual measures, 34 were observational and one was a randomised controlled trial. They were carried out in Asia (11), the United States (9), Europe (7), the Middle East (3), Africa (3), South America (1), and Australia (1).
Results from 8 of these 35 studies were analysed in detail, which indicated a statistically significant 53% reduction in the incidence of covid-19 with mask wearing and a 25% reduction with physical distancing.
Handwashing also indicated a substantial 53% reduction in covid-19 incidence, although this was not statistically significant after adjusting for the small number of studies included.
Detailed analysis was not possible for other measures, including quarantine and isolation, universal lockdowns, and closures of borders, schools, and workplaces, due to differences in study design, outcome measures and quality.
The researchers point out that high quality evidence on the effectiveness of public health measures is still limited. However, their comprehensive search strategy to identify and select studies for review minimised bias and suggests the results are robust.
As such, they conclude that personal and social measures, including handwashing, mask wearing, and physical distancing are effective at reducing the incidence of covid-19, while more stringent measures, such as lockdowns and closures of borders, schools, and workplaces “need to be carefully assessed by weighing the potential negative effects of these measures on general populations.”
Further research is also needed to assess the effectiveness of public health measures after adequate vaccination coverage, states lead author Dr Stella Talic at Monash University, Australia.
The lack of good research on public health measures for covid-19 is a pandemic tragedy, argue researchers led by Professor Paul Glasziou at Bond University, Australia in a linked editorial.
Considering the central importance of public health and social measures for initial pandemic control, the uncertainties and controversies around their effects, and the immense research effort being put into vaccine and drug development, this lack of investment in research on public health measures is puzzling - at just 4% of global research funding for covid-19, they explain.
They point to a recent initiative by the World Health Organization, backed by the Norwegian government, to strengthen “the global evidence base to provide actionable and evidence-informed guidance on such measures for decision-makers” as a positive development.
But they warn that this is only achievable if the global community of public health researchers, practitioners, and decision makers are ready and have the capacity to conduct the much needed trials, and funders are ready to fund them.
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