Data from multiple countries demonstrate that lifting restrictions imposed to reduce the spread of coronavirus disease 2019 (COVID-19) would result in a resurgence of infections, according to provisional analyses published in the European Respiratory Journal.
Most countries with significant COVID-19 outbreaks have introduced social distancing or “lockdown” measures to reduce viral transmission, however, the question of when, how, and to what extent these measures can be lifted remains.
Researchers used publicly available data up to May 21, 2020, to fit regression models for estimating trajectories to determine doubling times and the reproduction number (R0) of the disease before and during control measures. They found that before lockdown, the estimates of R0 were consistent with previously published data (between 2.0 and 3.7 in countries with the largest number of cases available for analysis [United States, Italy, Spain, France, and the United Kingdom]).
Little evidence suggests that these restrictions have reduced R far below 1 in many places, with France having the most rapid reductions (-R0 0.76 based on cases and 0.77 based on mortality). Intermittent lockdown has been suggested as a means for controlling the outbreak while allowing periods of increased freedom and economic activity. However these data suggest that few countries could have even 1 unrestricted week per month without seeing a resurgence of the epidemic. Another suggestion has been to restore 20% of the activity that has been prevented during lockdown, but even that appears to be difficult to reconcile for preventing the resurgence of the disease in most countries.
“In summary, a simple analysis based on the behaviour of the SARS-CoV-2 [severe acute respiratory syndrome coronavirus-2] pandemic to date across 73 countries suggests remarkably consistent effects of both exponential growth and slow decline in cases and mortality,” stated the authors. “Without a vaccine, these estimates are incompatible with a return to previous activities post ‘lockdown.'”
Lonergan M, Chalmers JD. Estimates of the ongoing need for social distancing and control measures post-“lockdown” from trajectories of COVID-19 cases and mortality [published online June 1, 2020]. Eur Respir J. doi:10.1183/13993003.01483-2020