Although Passover ends later this week, the government has yet to announce an organized exit strategy to help ensure that the country does not socially and economically implode while the public sits in isolation.
A team of Bar-Ilan University researchers, led by Baruch Barzel of the Department of Mathematics, says it has a solution: alternating lockdowns.
First, the population will be split into two groups, Barzel told The Jerusalem Post. Then, these groups will alternate between lockdown and routine activity in weekly succession. At the same time, those who show symptoms of the novel coronavirus – fever, coughing or difficulty breathing – will be isolated.
“Together with the adoption of everyday prophylactic behaviors, this strategy can help defeat the virus, while sustaining socioeconomic activity at a 50% level,” Barzel explained. “We found that employing our strategy significantly reduces the spread and helps flatten the curve.”
These two groups of citizens will have little if any interaction, which would already slow the coronavirus spread. However, its main advantage is that it helps isolate the “invisible spreaders” – those who are asymptomatic or who became infected during their active week and don’t show symptoms until further on in the incubation period.
"Consider an individual who became infected during their active week: They are now in their pre-symptomatic period – the most dangerous stage,” Barzel said. “The crucial point is that, according to the alternating lockdown routine they are now scheduled to enter their lockdown phase.”
He said that while they are at home the next week, they will most likely begin to exhibit symptoms, and therefore remain in isolation until full recovery.
“If following a week of lockdown they show no symptoms, they are most likely uninfected and can partake in social and professional activities during their active week,” he continued. “Therefore, alternating lockdown with full isolation of symptomatic spreaders ensures that at all times, the majority of invisible spreaders are inactive.
“Because we are synchronizing with the natural cycle of the disease, we are effectively isolating the invisible spreaders,” he concluded.
Barzel maintained that just by splitting the population, you are already reducing the amount of interaction and thereby lowering the infection rate. But, he said, “for COVID-19 this is not enough.” As such, sick people – whether they have tested positive for the virus or not – would be isolated at all times.
Barzel and his research team simulated the spread of COVID-19 using the SEIR model, assuming that people carry lifelong immunity to a virus or other disease upon recovery. But for many diseases, the immunity after infection wanes over time, which would allow recovered individuals to return to a susceptible state.
“This model tracks the number of individuals as they transition between the different stages of the disease: susceptible (those available to contract the disease), exposed (those who are at their pre-symptomatic stage), infected (those who develop symptoms) and recovered (those who are already immune),” a release provided by the university explained.
Moreover, the researchers accounted for a fraction of defectors who continue to be active even during their lockdown phase, as well as exempt individuals, such as essential workers.
“In a perfect world, we could cure the disease in two weeks, but the world is not perfect,” Barzel said. “Some people take more than a week to show symptoms and some people don't exactly abide by the rules. Our model allows for some people to take a week and a half to develop symptoms – and we miss those people, and they will go out and infect others.”
Even if around 15% violate their lockdown, “we will still kill the disease rather efficiently,” according to the model.
The best way to create these two groups, he said, is to work with local authorities who will divide up their constituencies by address. Then, entire buildings would be on lockdown or free to move about, also reducing infection, since residents of apartment complexes use the same elevators, staircases and more.
At the same time, whole families will be included in shifts, so that schools are open and children have school on the same weeks that their parents work. The government would have to inform businesses to operate at 50% and arrange their workers based on their pre-assigned shifts.
“For 90% this will be enough,” he said. “As long as school and work are aligned, then the only reason to break isolation would be if you really want to go to the shopping mall. Some people will do that.”
But he said that there is an option to use an app that would indicate if a person is supposed to be in or out of isolation. If the person is supposed to be on lockdown and he approaches the mall, the guard could check his or her app. If there is a green light he could enter. If red, he would be turned away.
Barzel said Israel can “take risks” as long as the number of people hospitalized and in need of intubation stays below 2,000. His plan keeps the country at an average of 1,600 people on ventilators, he said.
"We can achieve more if we also adopt responsible behavior,” he added, and therefore those not on lockdown would still be encouraged to wear masks and stay two meters apart from one another.
The team’s mathematical analysis and numerical results, including all their codes, was recently published on the arXiv open-access digital repository, and has gained traction.
Barzel and his team are working with the National Security Council and have presented the strategy to the academic committee advising the government. They were also contacted by international groups in the US advising 17 governments around the world. Barzel has consulted with officials in Italy and Brazil, too.
He told the Post that “there is a good chance” alternating lockdowns will be implemented as part of any exit strategy.