Attempts at restricting people’s mobility to control the spread of COVID-19 may be effective only for a short period, researchers said. A new study examines people’s mobility for seven months during the pandemic in the United States using publicly available, anonymized mobile phone data.
Reported in the Journal of Transport Geography, the study alerts authorities to the need for more manageable travel restrictions and policies that reduce COVID-19 exposure risk to essential workers – who, because they are required to be physically present at their workplaces, remained highly mobile during the pandemic.
The longitudinal study is one of the first to compare mobility data using a broad range of people over an extended period, rather than a cross section of data from a single point in time, the researchers said.
"The longitudinal approach allowed us to differentiate between two distinct waves over our study period: a first wave from March to June and a second wave from June to September,” said Junghwan Kim, a graduate student in geography and geographic information science at the University of Illinois Urbana-Champaign who led the research with Mei-Po Kwan, a geography professor at The Chinese University of Hong Kong and Kim’s doctoral advisor. “This approach also allowed us to look for relationships between mobility change and various social, spatial, policy and political factors.”
The study used mobile device data from 2,639 of the 3,000 U.S. counties, excluding those with too little data, those with excessively high mobility levels and those with incomplete demographic data.
“We found that, overall, mobility declined sharply in March and April but quickly recovered to the pre-pandemic mobility levels from April through June, forming a V-shaped data curve,” Kim said. “During the second wave that occurred between June and September, we saw very little change in mobility despite the COVID-19 pandemic becoming more severe.”