'Prolonged or intermittent' social-distancing measures are likely to be needed, perhaps until 2022, Harvard researchers say

"Prolonged or intermittent" social-distancing measures may be needed until 2022, to keep resurgent cases of covid-19 from overwhelming the U.S. health-care system, says a study by researchers at the Harvard T.H. Chan School of Public Health.

“Social distancing measures may need to last for months to effectively control transmission and mitigate the possibility of resurgence,” they write in the journal Science. “Intermittent distancing may be required into 2022 unless critical-care capacity is increased substantially, or a treatment or vaccine becomes available. . . . Recurrent wintertime outbreaks ... will probably occur.” And they warned that in such outbreaks, “The post-intervention resurgent peak could exceed the size of the unconstrained epidemic.”

As other experts have done, the researchers stressed the need for blood testing for antibodies, to understand the behavior of the virus and the immunity it causes, and provide for public health. Until those things are known, responses to the pandemic will include much guesswork.

The study "looked at a range of scenarios for how the SARS-CoV-2 virus will spread over the next five years," Stat reports. "Those scenarios included variables like whether people who are infected develop short-term immunity — less than a year — or longer-term protection. But overall, the research concludes it is unlikely that life will return any time soon to the way it was before the virus’ emergence."

Hopes that the virus would be "eradicated by intensive public health measures after causing a brief but intense epidemic" are fading, the study reports. "Increasingly, public health authorities consider this scenario unlikely." The researchers say the virus could resemble pandemic influenza, "circulating seasonally after causing an initial global wave of infection. . . . Distinguishing between these scenarios is key for formulating an effective, sustained public-health response." In addition to questions about seasonal variation, other unknown factors include "the duration of immunity and the degree of cross-immunity [with] other coronaviruses, as well as the intensity and timing of control measures," they write.

The researchers' model, based on the behavior of two similar coronaviruses in the U.S.. "predicts that a one-time social distancing effort of the type currently being employed in most parts of the country will not stop transmission of the virus," Stat's Helen Branswell writes. "If treatments are developed that can prevent covid-19 patients from progressing to severe disease or if a vaccine is developed, movement restrictions could be loosened without health care capacity being overwhelmed, the researchers said."

The senior author of the study, Mark Lipsitch, "said loosened restrictions could come sooner if scientists discovered that a lot more people have been infected already and have some immunity. He and his co-authors stressed how critical it is to conduct long-term serology studies designed to map out human immune responses to the virus over time," Stat reports. He told Branswell: “On the other hand, there are some indications coming out at the moment that not every case of covid-19 infection … generates a robust immune response, which would mean that the build up of herd immunity is slower than it's anticipated here.”