But the policy is intense. For just a handful of cases, measures have included strict border closures, localised lockdowns, travel restrictions, and the mass testing of tens of millions of people. Homebound flights booked by Chinese citizens who live abroad are often cancelled at the last minute.

On Thursday, a high-speed train from Shanghai was ordered to halt midway before arriving in Beijing, after an attendant was identified as a close contact of a Covid-positive patient. All the other 211 passengers onboard were immediately quarantined in designated places.

But as the world begins to slowly open up, having decided to live with the virus mitigated by vaccinations, China is one of the few still clinging to a strategy of elimination. Analysts and health experts are starting to ask how long it can last, and the latest outbreak – which began early this month – is again testing the limits.