How much is coronavirus spreading under the radar?

Is it time to ditch the idea of containing COVID-19?

Absolutely not, say Farrar, Armstrong and Kerkhov. Farrar explains that containment and mitigation strategies overlap because measures that help to prevent an outbreak spreading also mitigate its effects on lives and hospitals. The most basic containment measure entails testing to identify infected people, finding their contacts and preventing them from infecting others. The WHO credits the curbing of China’s outbreak to the country’s meticulous identification of cases and contacts. Chinese authorities quarantined contacts — at home and in facilities where they were monitored for 14 days.

“Sometimes people have hundreds of contacts, so that is a very intensive effort,” says Farrar. “But it’s absolutely critical to do it, because even though it probably won’t completely contain the outbreak, it buys you time to make sure hospitals are ready, to think about the consequences of closing schools.”

China’s mitigation measures, such as banning large gatherings, also seem to have slowed transmission. Armstrong uses an epidemiological measurement called the basic reproduction number, or R0, to describe the number of people whom an individual with COVID-19 might infect. “We are estimating an R0 of around two or three,” he says. “If we can more than halve that with mitigation strategies, the outbreak will no longer grow.”