Harvard: Intermittent social distancing will have to continue into 2022

TL;DR:
First figure:
Assumes this is not seasonally affected: A 4 week social distancing does practically nothing. A 20 week social distancing is the best case scenario.

Second figure:
Assumes this is seasonally affected: The best case scenario is no social distancing at all and we achieve herd immunity before June. Social distancing makes the epidemic worse by saving everyone for the autumn rush.

Third figure:
Third option they present is 10+ intermittent periods of social distancing until 2022. This will save the most lives, but will absolutely destroy the economy.

LINK

Abstract

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The SARS-CoV-2 pandemic is straining healthcare resources worldwide, prompting social distancing measures to reduce transmission intensity. The amount of social distancing needed to curb the SARS-CoV-2 epidemic in the context of seasonally varying transmission remains unclear. Using a mathematical model, we assessed that one-time interventions will be insufficient to maintain COVID-19 prevalence within the critical care capacity of the United States. Seasonal variation in transmission will facilitate epidemic control during the summer months but could lead to an intense resurgence in the autumn. Intermittent distancing measures can maintain control of the epidemic, but without other interventions, these measures may be necessary into 2022. Increasing critical care capacity could reduce the duration of the SARS-CoV-2 epidemic while ensuring that critically ill patients receive appropriate care.

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Figure 1. (A-D) Simulated prevalence of COVID-19 infections (solid) and critical COVID-19 cases (dashed) following establishment on 11 March 2020 with a period of social distancing (shaded blue region) instated two weeks later, withthe duration of social distancing lasting (A) four weeks, (B) eight weeks, (C) twelve weeks, and (D) twenty weeks. There is no seasonal forcing; R0 was held constant at 2 (see Figure S4 for R0 = 2.5). The effectiveness of socialdistancing varied from none to a 60% reduction in R0. Cumulative infection sizes are depicted beside eachprevalence plot (E-H) with the herd immunity threshold (horizontal black bar). Long-term (20-week), moderatelyeffective (20%-40%) social distancing yields the smallest overall peak and total outbreak size.

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Figure 2. (A-D) Simulated prevalence, assuming seasonal forcing (wintertime R0 = 2, summertime R0 = 1.4), of COVID-19 infections (solid) and critical COVID-19 cases (dashed) following establishment on 11 March 2020 with a period of social distancing (shaded blue region) instated two weeks later, with the duration of social distancing lasting (A) four weeks, (B) eight weeks, (C) twelve weeks, and (D) twenty weeks (see Figure S5 for a scenario with wintertime R0 = 2.5). The effectiveness of social distancing varied from none to a 60% reduction in R0. Cumulative infection sizes are depicted beside each prevalence plot (E-H) with the herd immunity threshold (horizontal black bar). Preventing widespread infection during the summer can flatten and prolong the epidemic but can also lead to a high density of susceptible individuals who could become infected in an intense autumn wave.

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Figure 3. SARS-Cov-2 prevalence (black curves) and critical cases (red curves) under intermittent social distancing (shaded blue regions) without seasonal forcing (A, C) and with seasonal forcing (B, D). Distancing yields a 60% reduction in R0. Critical care capacity is depicted by the solid horizontal black bars; (A) and (B) are the scenarios with current US critical care capacity and (C) and (D) are the scenarios with double the current critical care capacity. The maximal wintertime R0 is 2 and for the seasonal scenarios the summertime R0 is 1.4. Prevalence is in black and critical care cases are in red. To the right of each main plot (E-H), the proportion immune over time is depicted in green with the herd immunity threshold (horizontal black bar).

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