Harvard study says we could need bouts of social distancing until 2022

"We found that one-time social distancing measures are likely to be insufficient to maintain the incidence of SARS-CoV-2 within the limits of critical care capacity in the United States," news agency AFP quoted lead author Stephen Kissler as saying.

"What seems to be necessary in the absence of other sorts of treatments are intermittent social distancing periods," the agency added.

Widespread viral testing would be required in order to determine when the thresholds to re-trigger distancing have been crossed, it said quoting the authors.

The duration and intensity of lockdowns can be relaxed as treatments and vaccines become available while also allowing hospitals time to increase critical care capacity to cater for the surge in cases that would occur when the measures are eased.

"By permitting periods of transmission that reach higher prevalence than otherwise would be possible, they allow an accelerated acquisition of herd immunity," AFP quoted co-author Marc Lipsitch as saying.

The paper also questions “too much social distancing” and says “Under one modelled scenario — the social distancing was so effective that virtually no population immunity is built”.

The authors, however, do acknowledge that the lack of information about an infected person’s immunity history and its durability is a drawback in their model.

The authors said they are certain that the virus is here to stay and it was highly unlikely that immunity will be strong enough and last long enough that COVID-19 will die out after an initial wave, as was the case with the SARS outbreak of 2002-2003.

Antibody tests that have just entered the market and look for whether a person has been previously infected will be crucial in answering these vital questions about immunity, they argued.

A vaccine, which experts have warned remains more than a year away, will be the ultimate weapon against the coronavirus, the report added.