Time-variant strategies for optimizing the performance of non-pharmaceutical interventions (NPIs) in protecting lives and livelihoods during the COVID-19 pandemic

Wei Aun Yap; Dhesi Baha Raja

Diminishing marginal returns for extending prolonged lockdowns. The extra 70 days of a 120day of lockdown, compared with a 50-day lockdown, merely delayed the peak day of incidence by 20 days and did not prevent a resurgence of COVID-19 as the population remains non-immune after the intervention. Under the epidemiological parameters and population characteristics simulated for this hypothetical population, none of the C-series 'smash-the-mountain' strategies were able to eradicate COVID-19 fully, even in this closed population of 100,000. The technical strength of the stochastic ICM model used for these simulations, compared to deterministic compartment models, is that full eradication is a possible outcome as individuals are modelled discretely. Unless a vaccine is expected, a prolonged lockdown with an intensity much greater than that required to keep COVID-19 cases within health system capacity, but which is not able to eliminate the infection, is of unclear value. These C-series scenarios are among the worst performing strategies.