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IDE Releases First Comprehensive Evaluation of U.S. COVID-19 Reopening Policies

September 08, 2020

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The First Comprehensive Study of State-by-State Reopenings Shows Ad Hoc Policies Exacerbate COVID

Why is COVID-19 still flaring up more than six months after its initial surge in the U.S.? Why haven’t shelter-in-place, shut-downs, and social distancing effectively stopped the spread of the pandemic, and why are restrictions being re-imposed?

The answers to many of these vexing public health questions can be found in the first large-scale study of the impact of reopening on mobility, released today by MIT researcher Michael Zhao and MIT Initiative on the Digital Economy (IDE) Director, Sinan Aral. The study of cross-state spillovers and the effects of cross-state policies is based on more than 22 million mobile devices, social media connections among 220 million U.S. Facebook users, and U.S. state-level closure and reopening policies from January 1 to July 1, 2020 .

Sinan Aral
Michael Zhao

Put simply, the findings highlight the urgent need to coordinate COVID-19 re-openings across regions and the risks created by ad hoc local shutdowns and re-openings. It’s clear that countries that reopen without national coordination face significant difficulty controlling the resurgent spread of the coronavirus.

The analysis found that while closures reduced mobility by 5%-6%, once a state reopened, mobility returned to pre-pandemic levels. The explanation is clear: People flee from shuttered states or counties to open ones.

The uncoordinated opening, closing and reopening of states and counties, may actually be making the COVID problem worse, according to the authors. Building on methods from their previous work published in the Proceedings of the National Academy of Sciences, Aral and his team released the new study of the impact of state-by-state reopenings on the COVID pandemic. They found that reimposing local social distancing or shelter-in-place orders after reopening may be far less effective than policy makers would hope.  

In fact, such closures may actually be counterproductive as they encourage those in locked down regions to flee to reopened regions, potentially causing new hotspots to emerge. This analysis demonstrates that travel spillovers are not only systematic and predictable, but also large and meaningful.

For instance, Arizona was one of the first states to open businesses, but in late June, bars, gyms, movie theaters, and water parks were shut down for 30 days as the state became one of the virus’ new hot spots. Similarly, one month after dine-in restaurants, bars, and gyms were allowed to reopen in California, Governor Gavin Newsom made the country’s most aggressive reopening reversal amid his state’s spike in COVID-19 cases, shuttering all indoor dining, bars, zoos, and museums in the state. Similar reversals have occurred in Colorado, Florida, Louisiana, Michigan, New Mexico, Oregon, Texas, and West Virginia among other states.

“We’ve seen a patchwork of flip-flopping state policies across the country,” said Aral, senior author of the study. “The problem is that uncoordinated state reopenings, and even closures, create massive travel spillovers that are spreading the virus across state borders. If we continue to pursue ad hoc policies across state and regional borders, we’re going to have a difficult time controlling this virus, reopening our economy, or even sending our kids back to school.”

Fundamentally, “state policies have effects far beyond their borders,” Aral said. “We desperately need coordination if we are to control this virus.”

Among the key findings:

  • Counties under statewide shelter-in-place orders receive 8%-14% less cross-state traffic compared to pre-pandemic levels.
  • As expected, re-openings boost travel to destination counties—and their bars, restaurants and beaches– by 12%-13%.
  • When a location reopened and another was still locked down, people from lockdown counties flooded to the reopened destination–by 11%-12% from nearby counties, and 24% from distant counties.
  • If the origin location reopened but the destination was still closed, travel to both nearby and distant closed counties was curbed by 9%-17% and 21%-27% respectively.

“People flee closures and flood into newly reopened states,” Aral said, “we can’t avoid the travel spillovers caused by our ad hoc policies.”

The results highlight the importance of spillover effects when formulating national policy, and show the need for coordinated national and local policies across regions where spillovers are strong. 

Access the full working paper here.

Read the MIT Sloan Press Release here.


Sinan Aral, Director, MIT IDE
Sinan Aral Director, MIT IDE, and author of the new book, The Hype Machine, How Social Media Disrupts Our Elections, Our Economy, and Our Health–and How We Must Adapt
Michael Zhao PhD Candidate, MIT Sloan School of Management