New preprint with @ctedijanto, @mlipsitch and @yhgrad: “Social distancing strategies for curbing the #COVID19 epidemic” now available on dash.harvard.edu/handle/1/42638…
We expand upon a mathematical model of SARS-CoV-2 in the US to address the following questions: How long do social distancing measures need to stay in place? What if we try “pumping the brakes” with repeated rounds? How is this affected by seasonality? medrxiv.org/content/10.110…
In agreement with a recent report, strong, one-time social distancing may suppress critical cases to within capacity, but infection will resurge and overwhelm capacity once measures are lifted. imperial.ac.uk/media/imperial…
We show that if social distancing is relaxed when transmissibility is heightened in the fall, an intense winter outbreak may occur in the still mostly-susceptible population. This peak may be higher than the ‘no intervention’ case and will overlap with flu season. 
Intermittent social distancing can prevent critical care capacity from being exceeded but such measures may be required for 12-18 months. Depending on R0 and the amount of seasonality, social distancing must be ‘on’ for as little as 25% but up to 70% of the time.
Increased critical care capacity (doubled capacity shown here) is crucial to enable more patients to receive care they need while allowing population immunity to accumulate more rapidly and reducing the overall duration of the epidemic and the total length of social distancing.
Serological data can help us measure the true extent of population immunity to SARS-CoV-2. If many cases are undocumented and lead to immunity, less social distancing may be required than is estimated by our model.
In summary - on its own, social distancing may need to be maintained intermittently into 2022 to avoid overwhelming critical care capacity. Increased capacity and additional interventions such as contact tracing, therapeutics, and vaccines are urgently needed to ease this burden.
