Social Distancing Strategies Dramatically Reduced Coronavirus Spread

Economists looked at social distancing strategies adopted in U.S. counties in the past two months and the impact they had.

Shelter-in-place orders and other social distancing strategies have reduced by 10 to 35 times the spread of the coronavirus, according to an analysis in Health Affairs.

The study–led by economists at the University of Kentucky– looked at four social distancing adopted in U.S. counties from March 1-April 27, including shelter in place, bans on large gatherings such as sports events, public school closures, the shuttering bars and restaurants.

The UK modeling determined that the social distancing measures reduced the growth rate of confirmed COVID-19 cases by 9 percentage points after 16 days and suggests that the number of cases would have been 35 times higher without any of the measures.

In other words, without social distancing measures, the United States would now be contending with 35 million COVID-19 cases, rather than about 1.4 million confirmed cases.

"The numbers are eye-popping but illustrate the enormous power of exponential growth," study senior co-author Prof. Aaron Yelowitz said.

The study determined that shelter-at-home orders and closing entertainment venues had a greater effect on slowing the spread of the virus than did banning large social gatherings and closing public schools.

"There are many potential reasons and our arguments for non-findings are speculative, although we think it could be the case that those measures simply displace social interactions rather than reducing such interactions," Yelowitz said. "For example, if parents congregate in parks when schools close, it's possible that coronavirus is spread approximately the same."

Senior co-author Prof. Charles Courtemanche said that "most large events — like March Madness — were already being canceled anyway prior to any official prohibitions, which may have made these prohibitions redundant."

Courtemanche said the UK model "suggest that light measures don't work, and strong measures do."

"But they don't really say anything about intermediate measures — like opening restaurants at reduced capacity, or allowing socialization with masks," he said. "Since we don’t know what each intermediate step towards reopening will do, it makes sense to go one step at a time and look carefully for signs that the rate of spread is picking back up."

Yelowitz said states in the process of reopening should "watch some of the early openers to see what happens."

"Given exponential growth, the rise in cases often looks unimpressive until right before things explode," he said.