“Decision makers — pay attention to the math: emerging from lockdowns requires a gradual and phased approach to keep infection under control,” said Michael Bonsall from the Mathematical Ecology Research group at the University of Oxford, who helped lead the study team.
“Without this attention, you run the risk of burdening health systems with further waves of infection,” Bonsall told CNN.
But lockdowns have huge emotional costs and have crippled economies across the globe, including officially plunging the United States into a recession.
As spread of the coronavirus shows signs of slowing down in some parts of the world, governments — and individual states in the US — are grappling with how to reopen society without catastrophically driving up infection rates again.
Keeping an eye on numbers
“Furthermore, to increase the number of people that can be first released, lockdown should not be ended until the number of new daily confirmed cases reaches a sufficiently low threshold,” the research team wrote in their report.
The model isn’t foolproof; it depends heavily on two variables that are hard to pin down precisely. “We show that for the gradual release strategy that two model parameters — the infection rate and the recovery rate (or fatality rate) from the virus — are the biggest unknowns that influence our predictions,” said Bonsall.
“We also modelled an ‘on-off’ strategy, of releasing everyone, but re-establishing lockdown if infections become too high. We conclude that the worst-case scenario of a gradual release is more manageable than the worst-case scenario of an on-off strategy,” the group added in their report.
Even though the model focused on the population of the UK and the capacity of its health care system, it can be used in countries large and small, Bonsall said.
“The model is general and can be applied, with different parameters, across different countries and within regions/states within countries,” Bonsall said. The researchers did not specify which groups should be released first, but in the paper suggested younger people, who are on the whole less susceptible to getting severely ill. There are also other ways of dividing the population, said Bonsall.
Who goes first?
“Deciding which groups get released might depend on critical functions to the economy, decisions about education over economy growth, critical functions to local economies,” he said. “It also might be decided based on geography,” he added.
“This has huge ramifications and is all out of scope of our work but obviously critical to implementing the findings by decision makers.”
Dr. Amesh Adalja, an infectious disease doctor and a senior scholar at Johns Hopkins Center for Health Security, says transmission of the virus will certainly go up as people start to emerge from lockdown.
“You have to realize the virus isn’t going to go anywhere; it’s going to be present in that, as social mobility increases … you’re going to see an uptick in cases,” he told CNN. “The question will be, what is the trade-off between that uptick in case and the other aspects of people’s lives. How do you make that trade-off?”
Adalja said as long as hospitals have the capacity to treat the seriously ill patients, it’s up to individuals to decide what to do. “The only real exit strategy is going to be a vaccine, but because that’s not going to come from maybe two years or so, you have to make a decision on how you want to move forward,” he said.
As for the particular path for emerging from lockdown that is outlined in the paper, he said, in the US it is already too late, because many existing restrictions have already been loosened greatly in many places.