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Social Distancing May Need to Continue into 2022, Harvard Researchers Find

Harvard public health researchers published a study suggesting social distancing measures may stretch well into the future.
Harvard public health researchers published a study suggesting social distancing measures may stretch well into the future. By Melanie Y. Fu
By Virginia L. Ma, Crimson Staff Writer

Social distancing measures such as school closures and stay-at-home orders adopted to combat the coronavirus pandemic may need to continue into 2022, a team of scientists led by Harvard School of Public Health professors Marc Lipsitch and Yonatan H. Grad wrote.

The researchers used information about the novel coronavirus, formally known as SARS-CoV-2, as well as other human coronaviruses to formulate a five-year outlook of SARS-CoV-2 transmission, unveiling their findings in a report published Tuesday in the peer-reviewed journal Science.

Stephen M. Kissler, a postdoctoral fellow at the School of Public Health and an author on the paper, said the researchers outlined and modeled potential scenarios for the next few months based on current social distancing practices in place.

Kissler said the researchers wanted to investigate whether rates of infection would be effectively slowed by just one stint of social distancing.

“I think that there's sort of been this implicit understanding that we'll do one period of social distancing, that'll flatten the curve, and then we'll reach immunity in the population, and then we'll be done,” Kissler said.

Based on their models, however, the researchers found this assumption is likely not the case.

“Absent other interventions, a key metric for the success of social distancing is whether critical care capacities are exceeded,” they wrote in the report. “To avoid this, prolonged or intermittent social distancing may be necessary into 2022.”

Kissler said that, with each wave of social distancing, more people will develop immunity to the virus. As a result, the severity of interventions will be able to “let up a bit” while maintaining the same level of effectiveness.

As the report addresses, Kissler said the question of immunity remains the “key big unknown” about the virus.

Immunity from the coronaviruses that cause the common cold and milder illnesses is known to last only a year or two, while for more severe coronaviruses such as SARS and MERS, immunity after initial infection lasts three to five years, according to Kissler. For the novel coronavirus, he said researchers believe immunity will be “relatively short-lived."

“The question was whether it'll be long enough to sort of get us through this first pandemic wave and prevent another one from happening or not,” Kissler said.

The scientists warned in the report that, even with effective social distancing, the novel coronavirus could remain a threat for the next five years, depending on certain factors related to its immunity.

“Even in the event of apparent elimination, SARS-CoV-2 surveillance should be maintained since a resurgence in contagion could be possible as late as 2024,” they wrote.

Kissler said the wide variety of social distancing techniques being used across the globe will soon provide scientists much more information to compare the effectiveness of different measures in reducing transmission — essentially supplying a number of “natural experiments."

“My hope is that over time, we'll be able to tailor these interventions, so that they're sort of in the sweet spot where they're minimally disruptive but sort of maximally reduce transmission,” Kissler said.

In future work, Kissler said he hopes the models from the report can be adapted to develop localized predictions using data from different parts of the United States and countries across the world, tailored to each area’s climate, rate of contact between people, and age distribution.

“Before critical care capacity gets exceeded and before we cross these critical prevalence thresholds, we can see that, and then we can start adjusting their behavior accordingly,” Kissler said.

Ultimately, he said he envisions the integration of these models into day-to-day life.

“We can start doing things almost like weather forecasting, but it’s like COVID forecasting,” he said.

—Staff writer Virginia L. Ma can be reached at

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