Harvard Study Foresees Intermittent Isolation Measures Needed Until 2022

RIO DE JANEIRO, BRAZIL – Social distancing efforts to prevent the collapse of hospitals in the face of the Covid-19 pandemic may be required, albeit intermittently, until 2022. This is estimated by a group of researchers from Harvard University’s School of Public Health in an article published on Wednesday, April 15th, in Science magazine.

The scientists aimed to assess how the new coronavirus, which was named Sars-CoV-2, will remain among the human population for the next five years after the initial stage of the pandemic. They say that a practical solution will depend on whether we know exactly how long human immunity will last after infection or after vaccination.

In order to determine this, urgent serological studies will be required to determine the extent of the population’s immunity, whether it decreases over time, and if so at what rate. This epidemiological surveillance, they say, must be maintained in coming years to anticipate the potential for a resurgence of the disease.

The group, led by epidemiologist Marc Lipsitch, developed several scenarios for the spread of the disease until 2025, using estimates on seasonality, immunity and cross-immunity for other coronaviruses that cause common colds, taking into account data from time series in the United States.

They project that recurrent outbreaks of Sars-CoV-2 in winter will likely occur after the most severe initial pandemic wave, as with other respiratory viruses. Without other interventions — a vaccine, a specific treatment, or a substantial increase in intensive care (ICU) capacity — the only way to prevent health system collapse may be prolonged or intermittent social distancing until 2022.

“Additional interventions, including increased critical care capacity and effective therapy, would improve the success of intermittent distancing and expedite the achievement of herd immunity,” they write.

They report that serological studies will determine the extent and duration of immunity. “Even in the case of apparent elimination, surveillance of Sars-CoV-2 should be maintained, as a resurgence of contagion may be possible until 2024,” they write.

According to the researchers, the total incidence of the disease over the next five years will critically depend on whether or not the coronavirus will be in regular circulation among people, a question that is linked to the duration of immunity. For common colds, caused by other common coronaviruses among humans, immunity generally lasts one year. In estimates conducted in the study, scientists considered that immunity to Sars-CoV-2 induced by infection could last two years.

“Highly effective distancing could reduce the incidence of SarS-CoV-2 enough to enable a strategy based on contact tracing and quarantine, as in South Korea and Singapore,” they wrote. Otherwise, less effective distancing efforts “may result in a prolonged single peak epidemic, with increased pressure on the health system.”

Source: O Estado de S. Paulo