Mathematical modeling of COVID-19 transmission and mitigation strategies in the population of Ontario, Canada

Ashleigh Tuite; David N Fisman; Amy L Greer

In contrast to fixed-duration social distancing, we find that dynamic social distancing, with interventions turned on and off as needed, based on ICU capacity crossing a given threshold, represents a more effective, and likely more palatable, control strategy. Social distancing can be relaxed, but this inevitably results in resurgent disease in the population, requiring reinstatement. Nonetheless, dynamic social distancing is projected to maintain ICU capacity, and dramatically reduces overall attack rates, while at the same time requiring less total social distancing time than would be required by a fixed duration strategy of comparable effectiveness. Furthermore, dynamic social distancing has the potential to allow populations, and the economy, to "come up for air" at intervals, which may make this strategy more sustainable. We also found that a combination approach, with less restrictive social distancing along with enhanced case isolation and quarantine, could have a similar effect in the dynamic scenario as more restrictive social distancing alone. It is plausible that, as testing capacity increases, a combination approach that is less reliant on social distancing, will strike the right balance between disease control and societal disruption (30).