FRIDAY, May 15, 2020 (HealthDay News) -- Statewide stay-at-home orders appear to help slow the spread of COVID-19 above and beyond other steps like banning large gatherings and closing non-essential businesses.
That's the suggestion from a new cross-border study.
Certain counties in Iowa -- one of five states that didn't issue a stay-at-home order for its citizens -- experienced a 30% greater increase in COVID-19 cases compared to counties right across the border in Illinois, which did issue such an order, the researchers reported.
"It does line up with a lot of other evidence that's coming up from other national studies," said senior researcher George Wehby, a professor of health management and policy with the University of Iowa College of Public Health. "Overall, there's evidence the more restrictive measures were associated with greater declines in COVID case growth."
For this study, Wehby and a colleague compared COVID-19 rates for counties on either side of the Iowa/Illinois border. "Border counties serve as nice controls because they tend to be somewhat similar," Wehby said.
As the pandemic unfolded, Iowa issued a series of social distancing orders. The state banned gatherings and closed bars and restaurants, then closed non-essential businesses, and then closed all primary and secondary schools.
But Iowa did not issue a broad shelter-in-place order directing residents to stay home unless absolutely necessary, a step taken by Illinois on March 21.
The researchers found that the addition of a stay-at-home order was associated with a slower growth of cases in seven Illinois counties compared with eight neighboring counties in Iowa.
Within a month of the Illinois stay-at-home order, that state had nearly five fewer COVID-19 cases per 10,000 residents in border counties, compared with their neighbors across the line in Iowa, according to the report published online May 15 in JAMA Network Open.
Dr. Amesh Adalja, a senior scholar with the Johns Hopkins Center for Health Security, said, "It is not surprising that when a stay-at-home order is issued that you see a decrement in cases. The virus requires social interaction to transmit and a stay-at-home order delimits social interaction." Adalja was not involved with the new study.
"However," he continued, "the key metric is not necessarily the number of cases but the hospital stress load induced by the cases. Stay-at-home orders ideally should be issued with the primary aim of preserving hospital capacity."
It's important to know which social distancing measures work best as the world refines its response to COVID-19, Wehby said.
"Understanding what might be working more or less is a key question," Wehby said. "This study only adds a little more information into the bucket of evidence that needs to be accumulated."
For some unknown reason, stay-at-home orders appear to be associated with less transmission of the coronavirus, according to these results.
"These shelter-in-place or stay-at-home orders, there is something about them that seems to add above and beyond just closing restaurants," Wehby said.
"Do people behave differently even when they go out under a stay-at-home order?" Wehby pondered. "Are you more cautious? Do you keep a larger distance? Are you more likely to wear a mask or avoid being close to people? People with more health risks, are they more likely to stay home following these orders?"
The U.S. Centers for Disease Control and Prevention has more about COVID-19.
SOURCES: George Wehby, Ph.D., professor, health management and policy, University of Iowa College of Public Health, Iowa City; Amesh Adalja, senior scholar, Johns Hopkins Center for Health Security, Baltimore; May 15, 2020, JAMA Network Open, online