Title: The impact of policy interventions on SARS-CoV-2 transmission across 130 countries and regions

Abstract:

Introduction: Non-pharmaceutical interventions (NPIs) such as policies around containment, closure, economic measures and health systems actions are being used by countries to reduce transmission of SARS coronavirus 2 (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19). However, empirical evidence of the effectiveness of individual interventions has been inconsistent.

Methods: We used panel (longitudinal) regression to estimate the effectiveness of individual NPIs in reducing SARS-CoV-2 transmission in 130 countries with data from January - June 2020. First, we examined the temporal association between NPIs using hierarchical cluster analyses. We then regressed the time-varying reproduction number (Rt) of COVID-19 on NPI. We conducted sensitivity analyses around the temporal lag between NPIs and Rt, NPI intensity, variable-select criteria, and time-series truncation.

Results: We found temporal clustering between many of the NPIs, which complicated interpretation of findings. However, there was strong evidence for an association between two NPIs (school closure, internal movement restrictions) and reduced Rt. Another three NPIs (workplace closure, income support and debt/contract relief) had strong evidence that support effectiveness while moving from none to some efforts; two NPIs (public events cancellation, restriction on gatherings) had strong evidence support their effectiveness only when implemented at maximum capacity. Evidence for the remaining NPIs (stay-at-home requirements, public information campaigns, public transport closure, international travel controls, testing, contact tracing) was weaker.

Conclusion: Results need to be interpreted with caution since they indicate temporal associations rather than causation. However, the impact of school closure and internal movement restrictions is robust across different models. This provides empirical evidence for the potential effectiveness of the actions policy-makers around the world are taking to respond to the COVID-19 pandemic.