As the COVID-19 pandemic rages on unabated in countries around the world, there's a shared desire among those forced to shelter in place to see the extent to which social distancing is slowing the disease's spread. It's understandable -- collateral damage from government-imposed business closures threatens to devastate entire industries. As of this week, 26 million Americans have filed for unemployment claims, according to the U.S. Bureau of Labor Statistics, and the International Monetary Fund predicts a global financial crisis rivaling the Great Depression. Fortunately, a preprint study published by researchers at the University of Texas, the Southwest Research Institute, and the University of Texas Health Science Center in San Antonio strongly implies that quarantining and physical distancing are having the intended effects. Using a hybrid AI system dubbed SIRNet and several epidemiological models, which were trained on smartphone location data along with population-weighted density and other data points from the startup Safe Graph, World Health Organization, the U.S. Centers for Disease Control and Prevention, and elsewhere, the coauthors claim they managed to accurately predict the outcomes of various social distancing policies.
Reich and colleagues construct graphs of people in their various states of infection and the like among people, to simulate how COVID-19 spreads. Some share of the neighbors of a node which tests positive are traced and tested themselves." New work from Google scientists suggests that mass-testing of populations for the COVID-19 disease is not the way to go, given that infectious events may be heavily weighted toward the so-called super-spreaders, individuals in the population who have a larger-than-average number of contacts and tend to infect more people as a result. Scientists Ofir Reich and Guy Shalev of Google, and Tom Kalvari of Tel Aviv University, put together a simulation of the spread of COVID-19 using assumptions about people's networks of relationships. They offer two main takeaways.
To stem the spread of the new coronavirus, public health officials are recommending that when you enter public spaces, like a park or grocery store, you should wear a mask and keep at least 6 feet away from other people, even if they seem healthy. But with so much unknown about this virus, how did the experts come up with those recommendations, and how fail-safe are they when it comes to prevention? That metric -- 6 feet -- is pulled from guidance designed by the Centers for Disease Control and Prevention for medical providers to prevent the spread of infectious respiratory diseases between themselves and their patients in a health care setting. It's based on past studies of infection among health care workers, and specific to illnesses like the flu that are transmitted by respiratory droplets released when an infected person coughs, sneezes or even talks. Like the flu, novel coronavirus is believed to be transmitted primarily via those droplets.
Governments around the world are responding to the covid-19 pandemic, and social distancing is a central aspect of plans to limit the spread of the virus. But what is social distancing and how do you do it? What does social distancing mean? Social distancing practices are changes in behaviour that can help stop the spread of infections. These often include curtailing social contact, work and schooling among seemingly healthy individuals, with a view to delaying transmission and reducing the size of an outbreak.
Despite what members of the public may have heard earlier this week, on cable news, social media, or in video snippets of a few opaque sentences spoken by a World Health Organization official at a press briefing on Monday, the W.H.O. did not announce, report, or discover that people who are infected with the SARS-CoV-2 virus but have no symptoms hardly ever transmit it to others. They can and do spread the disease, and the W.H.O. As Michael Ryan, an Irish epidemiologist and a veteran of two Ebola epidemics and the campaign to eradicate polio, who is leading the W.H.O.'s response to COVID-19, said on Tuesday, "It's clear that both symptomatic and asymptomatic individuals are part of the transmission cycle." Ryan was speaking at a Facebook Live event that the W.H.O. had hastily convened to offer a "clarification" of remarks that his colleague Maria Van Kerkhove, an American epidemiologist who is the team's lead technical consultant, had made the day before, in which, out of context, she seemed to say that such transmission was "very rare," inspiring the startling headlines. There had been a "misunderstanding," Van Kerkhove said at the event; there was no new statement or policy, whatever the impression.