(CN) — At the onset of the novel coronavirus pandemic, U.S. health officials recommended communities practice physical distancing to help stem viral transmission. But cellphone data reveals that while some communities initially complied with health orders voluntarily, compliance dipped as the pandemic raged into the summer months.
The U.S. has more than 6.9 million confirmed cases of Covid-19, according to data gathered by Johns Hopkins University. And on Tuesday, the nation marked the tragic milestone of more than 200,000 deaths from Covid-19 — more than any other country in the world and a figure unimaginable at the beginning of the global pandemic.
The U.S. death toll has more than doubled over the last four months and is now larger than the number of American soldiers killed in World War I and the Vietnam War combined.
Public health officials have called on communities to maintain good hygiene, wear a face covering and practice physical distancing to slow the spread of Covid-19, though strictness of the guidelines vary depending on the state.
Compliance with physical distancing guidelines also vary and the differences in behavior are tied closely to demographics, according to the study by Louisiana State University, Baton Rouge researchers.
A computational analysis of U.S. cellphone location data showed Covid-19 “hotspots” occurred where physical distancing levels were low, according to the study published Tuesday in the journal PLOS ONE.
Rajesh Narayanan, the Louisiana State University professor who led the study, and his colleagues built a data model using “time spent at home” as the proxy for the physical distancing in counties throughout the United States.
Using the model to examine behavior in the first 21 weeks of Covid-19 spread in the U.S. — from late January to June — researchers found physical distancing increased nine-fold from January through late March, and then decreased by half through mid-June.
Researchers found “clusters” of low physical distancing behavior in counties that later experienced surges in Covid-19 infections.
Understanding the difference between asking people to voluntarily comply with guidelines and enforcing restrictions could also be a major factor in stemming viral spread, according to the study.
Narayanan said in a statement that the study shows encouraging voluntary physical distancing could be a more effective and cost-effective alternative to strict governmental restrictions.
“Cellphone location and mobility data reveal that social distancing in the U.S. during the Covid-19 pandemic was initially voluntary rather than a response to governmental jurisdictional restrictions,” Narayanan said. “As the pandemic progressed, both effects reinforced each other, increasing social distancing far more than what could be explained by the sum of the individual effects."
People with higher incomes were more likely to be able to physically distance from others and be at home with school age children or to care for children when day care centers were ordered closed, the study found.
Urban dwellers with college degrees initially stayed home less than people in rural areas but that changed closer to the summer months, likely because urban dwellers were able to work from home while those accommodations were less prevalent in rural regions, the study found.
“In the context of social distancing, a positive correlation between the fixed effect predictions and the demographic predictions suggests that the more restrictive counties also had individuals reducing their exposure, while the less restrictive counties had individuals taking on relatively more exposure,” the study said. “A negative correlation suggests that the actions of individuals and counties partially cancel.”
Researchers did not immediately respond to a request for further comment.
In California — which leads all states with 790,000 confirmed cases and over 15,000 deaths but also has a population of 40 million — officials have launched digital tools to help study viral transmission.
Los Angeles County leaders launched a mobile app that can anonymously notify a person if they came into close contact with someone who tested positive for the virus.
Makers of the SafePass app, which uses a phone’s Bluetooth to track a person’s interactions with others, will also send users at-home tests if they test positive for the virus.
The number of global coronavirus deaths is expected to surge past 1 million as early as next week.
Despite having only 4% of the global population, the U.S. has reported over 20% of global coronavirus deaths. With over 6.9 million confirmed cases, the country also leads India (5.5 million) and Brazil (4.5 million) in case totals.
Trailing the U.S. in total reported deaths is Brazil (137,000), India (88,000) and Mexico (73,000).
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