Systematic review of empirical studies comparing the effectiveness of non-pharmaceutical interventions against COVID-19

Abstract

Objectives: To evaluate which non-pharmaceutical interventions (NPIs) have been more and less effective in controlling the COVID-19 pandemic.

Methods: We performed a systematic review of published and unpublished empirical studies, either observational or interventional, analysing the comparative effectiveness of NPIs against the COVID-19 pandemic. We searched Embase/Medline and medRxiv to identify the relevant literature.

Results: We identified 34 studies. During the first wave of the COVID-19 pandemic, school closing was the most effective NPI, followed by workplace closing, business and venue closing and public event bans. Public information campaigns and mask wearing requirements were also effective in controlling the pandemic while being less disruptive for the population than other NPIs. There was no evidence on the effectiveness of public transport closure, testing and contact tracing strategies and quarantining or isolation of individuals. Early implementation was associated with a higher effectiveness in reducing COVID-19 cases and deaths, while general stringency of the NPIs was not.

Conclusions: In this systematic review, we found that school closing, followed by workplace closing, business and venue closing and public event bans were the most effective NPIs in controlling the spread of COVID-19. An early response and a combination of specific social distancing measures are effective at reducing COVID-19 cases and deaths. Continuous monitoring of NPIs effectiveness is needed in order to adapt decision making.

Keywords: COVID-19; Epidemic; Non-pharmaceutical interventions; SARS-CoV-2; Systematic review.

Fig. 1

PRISMA flow diagram for the selection of studies.

Fig. 2

Heatmap of the assessment of NPIs effectiveness in the studies analysing epidemic growth and incidence-related outcomes. The color grading is given according to the effectiveness ranking of each article. Darker green means higher effectiveness among the NPIs studied in the same article. Gray means no significant association with the outcome. White means the NPI was not studied. If no ranking was established, all the NPIs studied in the same article have the same shade of green. The rating provided is the result of the risk of bias analysis. Rt = time varying Reproduction number; g = growth rate; IRR1 = incident risk ratio of NPIs on the number of cases; IRR2 = incidence rate ratio; Growth* = epidemic growth expressed as ratios of rate ratios; CI = cumulative incidence. Pozo-Martin et al. 1 and 2: first and second waves.

Fig. 3

Heatmap of the assessment of NPIs effectiveness in the studies analysing mortality and death-related outcomes. The color grading is given according to the effectiveness ranking of each article. Darker green means higher effectiveness among the NPIs studied in the same article. Gray means no significant association with the outcome. White means the NPI was not studied. If no ranking was established all the NPIs studied in the same article have the same shade of green. The rating provided is the result of the risk of bias analysis. g = growth rate; IRR = incident risk ratio of NPIs on the number of deaths; CFR = case fatality rate.