Delayed implementation of, lower adherence to, and premature easing of social distancing results in an increase of coronavirus disease 2019 (COVID-19) cases, and could result in a rapid return to exponential growth of COVID-19, according to a study published in Annals of Internal Medicine.
The effectiveness of social distancing in areas with varying population demographic characteristics and adherence levels is unclear. Study authors used an agent-based simulation model study to determine how social distancing and adherence to social distancing affected Dane County, Wisconsin, the Milwaukee metropolitan area.
The model represented the social network and interactions in these regions while considering population demographic characteristics, asymptomatic disease transmission, limited testing availability, and age-specific adherence to social distancing measures. The primary outcome of this study was the total number of confirmed COVID-19 cases.
Study results demonstrated that increased cases of COVID-19 may be related to the delayed implementation of, lower adherence to, and premature easing of social distancing. In NYC, total number of confirmed cases would have been reduced by 80% if social distancing measures were implemented 1 week earlier (203,261 cases vs 43,366 cases by May 31), and would have been increased approximately 700% if implemented 1 week later (203,261 cases vs 1,407,600 cases by May 31). This effect varies depending on region. In Dane County, Wisconsin, implementing social distancing 1 week later would have increased total number of cases by 36% by July 31, whereas the same course would have decreased NYC cases by 539% in the same timeframe.
Study authors noted that earlier easing of social distancing measures would have increased confirmed cases, especially in combination with decreased adherence. In NYC, if social distancing measures were eased on June 1 instead of June 8 and there was a 5% decrease in adherence, confirmed cases would have increased from 224,194 to 230,932 as of July 31; if adherence had decreased by 15%, cases would have increased to 439,728 in the same timeframe. These results highlight the importance of personal behaviors since decreased adherence had a more pronounced effect than the date of easing social distancing measures.
“These findings highlight the importance of region-specific considerations, and ideally modeling, as inputs to making policy decisions for a given region,” study authors conclude.
Alagoz O, Sethi AK, Patterson BW, Churpek M, Safdar N. Effect of timing of and adherence to social distancing measures on COVID-19 burden in the United States: a simulation modeling approach. Ann Intern Med. Published online October 27, 2020. doi: 10.7326/M20-4096.