But what if this lasts for months or even years to come? That is the unnerving prospect raised by a paper published last week. Scientists at Harvard University suggested that periods of social distancing may be required until 2022 and possibly beyond, if hospitals are to avoid becoming overwhelmed by future waves of infection. If treatments and vaccines do not arrive quickly, we may need to steel ourselves for prolonged economic and social disruption.
One early hope was that the virus would burn itself out, as happened in the Sars epidemic, thanks to an unprecedented public health effort. Middle East respiratory syndrome, caused by a related but even deadlier coronavirus, has also shown limited spread.
This coronavirus, Sars-Cov-2, seems more persistent, perhaps because it can transmit before symptoms show. Countries that enacted early lockdowns now face the prospect of infections rising as restrictions ease. That puts this virus more in line with two less virulent coronaviruses, OC43 and HKU1, which circulate annually. Marc Lipsitch and Harvard colleagues modelled how Sars-Cov-2 might spread, informed partly by the seasonality and immunity pattern of its milder cousins.
The models, which stretch into 2025, also factor in possible cross-immunity from the other coronaviruses. “We projected that recurrent wintertime outbreaks of Sars-Cov-2 will probably occur after the initial, most severe pandemic wave,” the authors write in the journal Science. To avoid overwhelming intensive care, they add, “prolonged or intermittent social distancing may be necessary into 2022.” One scenario has the virus surging back in 2024.
The researchers do not advocate any course of action and their model, which uses US data, is based on many assumptions. But the prospect of living semi-permanently with the virus should focus minds on scientific strategies to liberate us from such a future.
A virus’s return spells trouble if a high share of the population remains susceptible. Only immunity, through infection or vaccination, can prevent that. Until vaccines are developed, only those who recover from infection have a chance of being immune. To stamp out the spread of the virus, about 60 per cent of the population needs immunity. We need widespread antibody testing to hint at how close we are to this threshold. Without this, we risk flying blind into a series of blunderbuss lockdowns.
Alternately, we could end lockdowns and expand healthcare to fit, so that herd immunity can be reached quickly. Yet it seems irresponsible to advocate widespread infection with a virus that was unknown four months ago, even if treatments exist and hospitals can cope. Covid-19’s long-term effect on survivors is uncertain; it ravages the heart and kidneys as well as the lungs and kills an estimated 0.7 per cent of those infected. It is also possible that infection confers only weak or brief protection, meaning herd immunity may never be reached. Allowing the virus free rein would be a high-stakes gamble for no return.
Our best exit strategy, then, is to do as Germany and South Korea did from the start: gather intelligence to inform a fluid response. These measures cover diagnostics, surveillance and mass testing, contact tracing, isolation and quarantine, while researching treatments and vaccines. There are ways of cutting infection risk while permitting some social mixing. A Cambridge university project on “resilient normality” has crowdsourced 275 suggestions: they include stripping doors of handles in public places, delivery drones, rotas for school attendance and free rental bikes to reduce transport overcrowding.
Any kind of normality lies some way off, but science offers the safest and quickest path out of the woods.
The writer is a science commentator