The stay-at-home orders that most states put into place last spring appear to have had a significant impact on slowing down the spread of the coronavirus, both nationally and in individual states, according to a study published in the Journal of Infectious Diseases.
A team of researchers, led by Mark Lurie, a professor of epidemiology at Brown University, looked state by state and nationally at how quickly COVID-19 spread before and after stay-at-home orders were implemented. They did this by calculating the pandemic’s doubling time — how long it took for confirmed COVID-19 cases to double.
“Increased doubling time indicates a slowing of the epidemic — more days are required for the cumulative number of cases to double,” they explain in their paper.
At the state level, the researchers began by calculating the pandemic doubling time during the period prior to each state’s stay-at-home orders, starting on March 4 (the day when 100 cumulative cases were reported nationwide). They then compared it to the doubling time in a period that began 14 days after each state’s orders were implemented — through April 30. (The 14 days permitted a “buffer” to allow for the minimum period of time for policy changes to impact the number of new cases.) For the five states that didn’t enact stay-at-home orders (Arkansas, Iowa, Nebraska, North Dakota and South Dakota), the researchers calculated the doubling time over the entire period.
To determine the national doubling time, they compared the doubling time of March 4-April 4 with that of April 5-April 30.
Key findings
The data revealed that before the lockdowns became widespread (March 4-April 4), the number of COVID-19 cases in the U.S. doubled in less than three days (2.68 days), indicating a rapid spread of the virus. After the lockdowns, the doubling time expanded by 460 percent— to an average of 15 days.
[image_credit]Brown University[/image_credit][image_caption]This map highlights the percentage increase in epidemic doubling time between pre-stay-at-home order and during stay-at-home order time periods, by state.[/image_caption]
Minnesota had the smallest increase in its doubling rate among the states that issued stay-at-home orders. Its pandemic doubling time went from every 5.89 days before March 27, when Gov. Tim Walz issued a stay-at-home order for the state, to every 9.20 days afterward — a 56 percent increase.
Louisiana had the biggest increase in its doubling rate, from every 2.99 days before its lockdown to every 29.41 days afterward — an 884 percent increase.
“These findings suggest that stay-at-home orders combined with varied levels of implementing CDC-recommended practices of testing, tracing and isolation, as well as travel restrictions, likely played a key role in significantly reducing the epidemic growth rate,” the study’s authors conclude.
Limitations and implications
The study relied on available COVID-19 data, which, as the researchers point out, likely under-reports the true number of cases in the U.S. In addition, the study is observational, which means it can’t prove a cause-and-effect relationship between the lockdowns and the increase in the COVID-19 doubling times.
Still, these findings are supported by previous studies that have made similar observations. Research published in May in the American Journal of Infection Control reported that the COVID-19 doubling rate increased from every 5 or 6 days to every 14 days after states locked down last March and April.
Also in May, University of Minnesota researchers reported in the Journal of the American Medical Association (JAMA) that stay-at-home orders were associated with a significant reduction in the number of Americans hospitalized for COVID-19
“We hope that these findings contribute to a growing body of evidence aimed at studying the full course of COVID-19 in America,” says Joe Silva, a co-author of the current study and a Ph.D. student at Brown’s School of Public Health, in a released statement.
“This study does not imply stay-at-home orders were the sole factor that drove the observed increase in epidemic doubling time, but the data may be representative of the impact of multiple public health measures,” he added.
FMI: You can read the full study on the website for the Journal of Infectious Diseases.
The study confirms both what was hoped for and what common sense implied. It’s the best that can be done with a deadly new virus that’s still being figured out.
Of course, I’m sure all are aware that epidemiologist Osterholm and Mpls Fed Reserve chair have called for a new, more robust national lock-down as the only way to stem the now raging Trump Pandemic, after the manifest incompetence show by Trumpolini so far. Studies like this clearly support that recommendation.
Unfortunately, as we can see from the recent Sturgis, SD “rally” and its celebration by that state’s (braindead) Repub governor, we don’t live in a nation populated by responsible adults or have a serious national government, so there is nothing less likely to occur than the nation following Osterholm’s expert advice.
Future historians will write that the 400,000 (or more) Americans that this pandemic ultimately will slay were sacrificed on the altar of Selfish Individualism.
Whoa, whoa, whoa! Hang on just a second. Does the author mean to suggest that social distancing and mask wearing would actually help us get this pandemic under control? That by following these protocols for a certain finite period we could get back to normal again fairly soon? Rev up the economy again before the first snow flies? Back in school by January 2021? Follow the science?
Forget it. I have my rights and I ain’t giving them up. Don’t want no guvment intrusion. I been on this here flat Earth for decades and ain’t nobody makin’ me wear a mask.