Optimal lockdown strategies for SARS-CoV2 mitigation— an Indian perspective

Abstract

We sought to identify optimal temporal windows for lockdown-based mitigation strategies on infectious disease spreads. An age-structured multi-compartmental Susceptible-Infected-Recovered (SIR) model was used to estimate infection spreads under parametric variation of lockdown intensity and duration from the data of SARS-CoV2 cases in India between January to July, 2020. The resulting parameter values were used to simulate lockdown outcomes for a wide range of start times and durations. Lockdowns were simulated as intervention strategies that modified weights assigned to social contact matrices for work, school and other places. Lockdown efficacy was assessed by the maximum number of infections recorded during a simulation run. Our analysis shows that lockdown outcomes depend sensitively on the timing of imposition and that it is possible to minimize lockdown durations while limiting case loads to numbers below the hospitalization thresholds. Such timing based effects arise naturally from the non-linear nature of SIR dynamics.

Optimal lockdowns for COVID‐19 pandemics: Analyzing the efficiency of sanitary policies in Europe

“…Starting date is the distance to the peak. ICU, intensive care unit 0.25 and which lasts till the end of the simulation horizon T = 300 (see Pathak et al, 2020). This corresponds to a waiting time for the appearance of a vaccine.…”

“…These are the two parameters to be found by optimization. But instead of returning to zero, there is a follow‐up period with mild conservatory sanitary measures of severity parameter that we fixed equal to 0.25 and which lasts till the end of the simulation horizon (see Pathak et al, 2020). This corresponds to a waiting time for the appearance of a vaccine.…”

“…Epidemiologic models such as the SIR model of Kermack and McKendrick (1927) and its variants are well designed to explore different counterfactual policy scenarios, which in the absence of a vaccine or a therapy, are all based on lockdowns with nontrivial psychological and economic consequences. Epidemiologists (Ferguson et al, 2020; Pathak et al, 2020; or Salje et al, 2020 to quote a few) are looking for lockdowns which are optimal for either reaching herd immunity, limiting the diffusion of the disease, preserving hospital capacity, avoiding a second wave, or a rebound in the epidemic.…”