https://www.youtube.com/watch?v=jYxiOJ8QxCE
Worst case
Some researchers find such predictions overly optimistic. People in most Chinese cities started returning to work last week after an extended public-holiday period — opening up the possibility of new chains of transmission, says Hiroshi Nishiura, an epidemiologist at Hokkaido University in Sapporo, Japan.
Nishiura says he has used a model that estimates that the outbreak will peak sometime between late March and late May. At this point, he says, up to 2.3 million cases will be diagnosed in a single day. In total, he estimates that between 550 million and 650 million people across China will be infected, roughly 40% of the country’s population. Nishiura says that about half of those people will show symptoms.
Nishiura says he has submitted a paper describing the model and its prediction to the preprint server medRxiv. To make such a prediction, he says that his team considered the transmission potential inherent to the new virus — the basic reproduction number known as R0, which is related to R, although it assumes that everyone in the population is susceptible to infection. The team estimates the R0 is between 1.5 and 2.
He says that his model presents a relatively simplistic outlook because it assumes that everyone in the population is susceptible. It also reflects the view that many people who have been infected are asymptomatic or not unwell enough to seek medical treatment. If that is the case, the current number of reported cases massively underestimates the number of people infected, he says.
Gabriel Leung, an epidemiologist at the University of Hong Kong, says that Nishiura’s estimates are feasible. The community has no immunity to SARS-CoV-2, the virus that causes COVID-19 so “it will sweep through”, he says.
Leung says that while those estimates sound extreme, it’s still not clear how deadly the virus is. The latest calculation of the fatality rate, in a paper published by Zhong on 9 February, suggests that there are about 1.36 deaths per hundred cases. But that number is probably too high because the authors did not consider less severe cases. (Outside China, two deaths have been reported in 500 cases.)
