Ever since China ended its “zero-Covid” policy late last month, its hospitals have been overwhelmed by cases. But as concerns grow about the threat of new variants Beijing has been criticised by global health bodies for a lack of transparency about the prevalence of the virus in the country.

At least 15 countries have introduced mandatory Covid testing for travellers arriving from China, mostly to ensure that no dangerous variants go undetected. The UK Health Security Agency, for example, has asked hospitals to sequence all viral samples from patients who have arrived from China that are hospitalised with Covid.

But are surging infection rates likely to lead to powerful variants from China or other countries with current high caseloads, such as the US? The chances are seen as low by many epidemiologists though they remain concerned that a lack of transparency in some countries could hinder detection.