What’s new: China's State Council released new guidelines on asymptomatic coronavirus cases saying those who test positive for the virus but show no symptoms, as well as their close contacts, will be subject to mandatory medical isolation.

The guidelines declare that asymptomatic cases are infectious, call for strong oversight and testing, and say doctors and hospitals should report new asymptomatic cases within two hours.

Asymptomatic carriers who undergo at least 14 days of medical observation and test negative in two consecutive nucleic acid tests at least 24 hours apart can be released, the guidelines say. Close contacts of such cases will also be placed in medical isolation for 14 days.

Those in the incubation phase of the disease are included in the government definition of “asymptomatic.”

The background: On April 1, under mounting pressure and amid public calls for transparency, China began publishing its previously secret count of asymptomatic cases in its daily Covid-19 reports.

Asymptomatic coronavirus cases are one of the many enigmas about Covid-19, with emerging medical evidence suggesting asymptomatic people can spread the virus, but experts differing on just how readily they might do so.

Definitions and estimates of the prevalence of asymptomatic infections vary widely: the World Health Organization says they are rare, but research from one virus-struck Italian village suggests up to 75% of cases could be asymptomatic.

The prospect of people spreading Covid-19 unknowingly has been called one of the biggest risks to China's battle against the disease.

Quick Takes are condensed versions of China-related stories for fast news you can use. To read the full Caixin article in Chinese, click here.

Contact reporter Flynn Murphy (yutonglu@caixin.com)