50 days in lockdown, 30 days of relaxation, could help contain COVID-19 pandemic

Business with a closed sign due to COVID-19.
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Social distancing has become the norm for controlling the COVID-19 pandemic, but keeping these measures in place for months on end could cause economic devastation. Now, a new study suggests a potential strategy for fighting COVID-19 while reducing economic impacts.

The study found that alternating between 50 days of strict lockdown and 30 days of relaxation of these measures could control the outbreak.

"This intermittent combination of strict social distancing, and a relatively relaxed period ... may allow populations and their national economies to 'breathe' at intervals — a potential that might make this solution more sustainable, especially in resource-poor regions," study lead author Dr. Rajiv Chowdhury, a global health epidemiologist at the University of Cambridge in England, said in a statement. The study, published Tuesday (May 19) in the European Journal of Epidemiology, was conducted by an international team of researchers known as the Global Dynamic Interventions Strategies for COVID-19 Collaborative Group. 

With a vaccine for COVID-19 at least a year away, some researchers have suggested that countries could cycle between periods of restrictions and relaxations to manage COVID-19. But how long these cycles should last wasn't clear.

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In the new study, the researchers used a mathematical model to simulate COVID-19 outbreak trajectories in 16 countries, representing a mix of high-, middle- and low-income countries. The authors then modeled several scenarios that alternated between easing social-distancing restrictions and reimposing them. 

The authors considered two types of restrictions: so-called "mitigation measures," which include things like school closures and restrictions on large public events; and more strict "suppression measures," i.e."lockdowns," which include more stringent social-distancing rules.

The researchers found that, with no restrictions at all, the number of COVID-19 patients that required intensive care (ICU care) would quickly outpace hospital capacity for all 16 countries and result in 7.8 million deaths.

In contrast, if countries implemented a cycle of 50 days of mitigation measures followed by 30 days of relaxation, the number of deaths would be reduced to 3.5 million across all 16 countries. In addition, the R0 (pronounced R-nought), or the average number of people who catch the virus from a single infected person, would be reduced from 2.2 to 0.8. (In general, the R0 needs to be below 1 to reduce disease transmission.) However, in this scenario, the number of patients requiring intensive care unit (ICU) care still exceeded hospital capacity in all 16 countries after about 3 months. The researchers estimate that in this scenario, the pandemic would last about 12 months.

A strategy involving strict "suppression measures" for 50 days, followed by 30 days of relaxation, yielded better results, reducing the R0 to 0.5 and deaths to just over 130,000, without exceeding hospital capacity, the authors said. However, because fewer people become infected with COVID-19 in this scenario (meaning fewer people likely had some immunity to it), the authors estimate that the pandemic would last longer, about 18 months.

"[A] significant number of new infections and deaths could be prevented if these 'rolling' suppression measures can be maintained for an 18-month period," or until a vaccine becomes available, the authors wrote.

Ultimately, it will be up to individual countries to define the specific durations of these interventions depending, , the authors said.

"Our study provides a strategic option that countries can use to help control COVID-19 and delay the peak rate of infections," study co-author Dr. Oscar Franco, director of the Institute of Social and Preventive Medicine at the University of Bern, Switzerland, said in the statement. "This should allow them to buy valuable time to shore up their health systems and increase efforts to develop new treatments or vaccines."

Originally published on Live Science.  

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Rachael Rettner

Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.