Evaluating the impact of non-pharmaceutical interventions for SARS-CoV-2 on a global scale

Abstract

In the absence of a viable pharmaceutical intervention for SARS-CoV-2, governments have implemented a range of non-pharmaceutical interventions (NPIs) to curb the spread of infection of the virus and the disease caused by the virus, now known as COVID-19. Given the associated social and economic costs, it is critical to enumerate the individual impacts of NPIs to aid in decision-making moving forward. We used globally reported SARS-CoV-2 cases to fit a Bayesian model framework to estimate transmission associated with NPIs in 26 countries and 34 US states. Using a mixed effects model with country level random effects, we compared the relative impact of other NPIs to national-level household confinement measures and evaluated the impact of NPIs on the global trajectory of the COVID-19 pandemic over time. We observed heterogeneous impacts of the easing of restrictions and estimated an overall reduction in infection of 23% (95% CI: 18-27%) associated with household confinement, 10% (95% CI: 1-18%) with limits on gatherings, 12% (95% CI: 5-19%) with school closures and 17% (95% CI: 6-28%) with mask policies. We estimated a 12% (95% CI: 9-15%) reduction in transmission associated with NPIs overall. The implementation of NPIs have substantially reduced acceleration of COVID-19. At this early time point, we cannot determine the impact of the easing of restrictions and there is a need for continual assessment of context specific effectiveness of NPIs as more data become available.

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

“…Zhang et al 20 analysed another relatively long study period until August, and several authors performed an analysis until July 2020 21 , 22 , 23 . Some authors standardised the start and/or end of the study period in order to be able to compare the effectiveness of NPIs across units of analysis at similar stages of the epidemic 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 .…”

“…Some focused on specific areas, with nine studies analysing data from the United States, performing mostly state-level 20 , 26 , 31 , 39 , 40 , 41 , but also county-level 22 , 42 , 43 analyses, three studies estimating the effects of NPIs in Europe 28 , 29 , 44 and two studies in all OECD countries 19 , 45 . Five studies selected specific countries that belong to different world regions 15 , 24 , 25 , 30 , 46 and three included both countries and US states 18 , 27 , 47 .…”

“…Twenty-seven studies analysed the relation between lockdown and the reproduction number, case growth rates and cases, and 18 out them (67%) found an association with their reduction. Five studies found lockdowns to be the most effective control measure 18 , 27 , 31 , 40 , 42 . Flaxman et al 29 found it to be the only measure reducing the reproduction number below one.…”

“…However, some high rated studies found public information campaigns to be among the least effective policies 36 , 47 . With respect to mask wearing requirements, three intermediate and high-quality studies 17 , 19 , 27 found it to be among the most effective measures. Chernozhukov et al 39 , found that the only significant measure reducing the case growth was implementing mask wearing requirements for employees in public facing businesses.…”

The tortoise and the hare: The race between vaccine rollout and new COVID variants

“…• Some research suggests that stay-at-home requirements are most effective in curbing the propagation of the virus (Esra et al, 2020;Gapen et al, 2020;Spiegel and Tookes, 2020;Chernozhukov et al, 2020).…”