The temporal association of introducing and lifting non-pharmaceutical interventions with the time-varying reproduction number (R) of SARS-CoV-2: a modelling study across 131 countries

Abstract

Background Non-pharmaceutical interventions (NPIs) were implemented by many countries to reduce the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causal agent of COVID-19. A resurgence in COVID-19 cases has been reported in some countries that lifted some of these NPIs. We aimed to understand the association of introducing and lifting NPIs with the level of transmission of SARS-CoV-2, as measured by the time-varying reproduction number ( R ), from a broad perspective across 131 countries. Methods In this modelling study, we linked data on daily country-level estimates of R from the London School of Hygiene & Tropical Medicine (London, UK) with data on country-specific policies on NPIs from the Oxford COVID-19 Government Response Tracker, available between Jan 1 and July 20, 2020. We defined a phase as a time period when all NPIs remained the same, and we divided the timeline of each country into individual phases based on the status of NPIs. We calculated the R ratio as the ratio between the daily R of each phase and the R from the last day of the previous phase (ie, before the NPI status changed) as a measure of the association between NPI status and transmission of SARS-CoV-2. We then modelled the R ratio using a log-linear regression with introduction and relaxation of each NPI as independent variables for each day of the first 28 days after the change in the corresponding NPI. In an ad-hoc analysis, we estimated the effect of reintroducing multiple NPIs with the greatest effects, and in the observed sequence, to tackle the possible resurgence of SARS-CoV-2. Findings 790 phases from 131 countries were included in the analysis. A decreasing trend over time in the R ratio was found following the introduction of school closure, workplace closure, public events ban, requirements to stay at home, and internal movement limits; the reduction in R ranged from 3% to 24% on day 28 following the introduction compared with the last day before introduction, although the reduction was significant only for public events ban ( R ratio 0·76, 95% CI 0·58–1·00); for all other NPIs, the upper bound of the 95% CI was above 1. An increasing trend over time in the R ratio was found following the relaxation of school closure, bans on public events, bans on public gatherings of more than ten people, requirements to stay at home, and internal movement limits; the increase in R ranged from 11% to 25% on day 28 following the relaxation compared with the last day before relaxation, although the increase was significant only for school reopening ( R ratio 1·24, 95% CI 1·00–1·52) and lifting bans on public gathe...

Forecasting the spread of COVID-19 under different reopening strategies

“…On the other hand, a return to a 75% level of the normalcy would cause cases to surge for about two months. The pattern of the surge is consistent with recent studies on the relaxation of non-pharmaceutical interventions such as shelter-in-place orders 18 . However, after two months cases would again reach a long-term plateau, although this would occur at a level that was almost double of what would be experienced under the early-August level of social distancing.…”

Early assessment of the impact of mitigation measures to control COVID-19 in 22 French metropolitan areas, October to November 2020

“…Temporal evolution of these parameters was described among three groups of metropolitan areas, constituted according to the measures implemented and their timing ( Table 1 ). Timing of mitigation measures were considered as the date of their implementation but, based on the natural history of SARS-CoV-2 infection and data on sampling delay, their effects are expected to be observable at least 1 week later [ 2 , 3 ].…”

Acceptability of Government Measures Against Covid-19 Pandemic in Senegal: a Mixed Methods Study

“…In all countries of the world, multiple forms of government measures have been implemented. Many studies have previously modelled their potential effects and then the reality of their effectiveness [3,6,7].…”