Stay-at-home orders nearly halted travel for most Americans by late March, an analysis of anonymous cellphone location data by The New York Times found. Americans in much of the Northeast,
Midwest and West complied with orders from state and local officials to stay home, the data suggests, but delays in enacting such orders in other areas, including parts of the Southeast, potentially dampened the impact of social distancing measures.
“It’s just math,” Natalie Dean, an assistant professor of biostatistics at the University of Florida, said. “If people dramatically reduce the number of people they’re interacting with, that will reduce the spread of the disease.”
“These types of strategies have worked,” she added.
But the many variables at play — beginning with the unpredictable nature of the virus — demand that the efficacy of these strategies be placed in context.
In the United States, there are the decisions by some states not to impose stay-at-home orders; the fears that warmer weather will lure people into socializing; and, especially, the low and inconsistent availability of testing, a fundamental tool in tracking the disease and preventing spread.
“What we’ve seen in the short term is that very stringent measures, that have a lot of societal impact, have been effective at reducing the rate of growth,” said Joseph Lewnard, an assistant professor of epidemiology at the University of California, Berkeley.
“Unfortunately, the flattening of the curve we see now does not necessarily paint a rosy picture about reopening society as it was before the epidemic,” he said.
Without a vaccine, any progress is fragile, temporary. The social distancing measures cannot continue forever. And if they are relaxed without meticulous testing and the isolation of new patients, researchers say, the numbers of infections and fatalities are likely to soar again.