As summertime trips end in Europe,  as well as in the United States and some students return to college campuses and primary schools worldwide, fresh waves of COVID infections are causing renewed restrictions after loosening in the spring and summer.

However, a new study reports this uncoordinated opening, closing, and reopening of states and counties are making the COVID problem worse in the U.S., according to the authors of a new study. Using methods from their previous work, published in the Proceedings of the National Academy of Sciences, MIT Ph.D. student Michael Zhao and Sinan Aral, director of the MIT Initiative on the Digital Economy and author of the upcoming book The Hype Machine, have released the first comprehensive study of the impact of state-by-state re-openings on the COVID pandemic, spanning January to July with surprising and troubling results.

After studying combined data on the mobility of more than 22 million mobile devices, daily data on state-level closure and reopening policies, and social media connections among 220 million Facebook users, the team found that reimposing local social distancing or shelter-in-place orders after reopening may be far less effective than policymakers would hope, according to a news release.

Further, such closures may 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.

Out West

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’s new hot spots. One month after dine-in restaurants, bars, and gyms were allowed to reopen in California, Gov. 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 ColoradoFloridaLouisianaMichiganNew MexicoOregonTexasWest Virginia among other states.

“We’ve seen a patchwork of flip-flopping state policies across the country,” said Sinan Aral, the senior author of the study in the news release. “The problem is that, when they are uncoordinated, state re-openings 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.”

The new study showed while closures directly reduced mobility by 5-6%, re-openings returned mobility to pre-pandemic levels. Once all of a state’s peer states (in travel or social media influence) locked down, focal county mobility in that state dropped by an additional 15-20% but increased by 19-32% once peer states reopened. “State policies have effects far beyond their borders,” Aral said. “We desperately need coordination if we are to control this virus.”

Sheltering in Place

When an origin county was subject to a statewide shelter-in-place order, travel to counties yet to impose lockdowns increased by 52-65%. If the origin had reopened, but the destination was still closed, travel to destination counties was suppressed by 9-17% for nearby counties and 21-27% for distant counties. But when a destination reopened while an origin was still closed, people from the closed origins flooded into the destination by 11-12% from nearby counties and 24% from distant counties.

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

These findings highlight the urgent need to coordinate COVID-19 reopenings across regions and the risks created by ad hoc local shutdowns and reopenings. Besides, the results highlight the importance of taking spillover effects seriously when formulating national policy and for national and local policies to coordinate across regions where spillovers are strong, according to the news release.

Source: MIT Sloan School of Management