A guard stands outside the Xinfadi market in Beijing, shuttered due to concerns of Covid-19. | Noel Celis/AFP/Getty Images

A huge market in Beijing is the source of a cluster of new infections.

China reported on Sunday that the country had 57 new confirmed cases of coronavirus as of midnight on Saturday — the highest number of infections it has reported in two months.

The spike in cases — which appear to have originated in a wholesale food market in Beijing — has caused Chinese authorities to selectively lock down at-risk areas, highlighting how countries seeking a return to normalcy after reducing transmission of the virus are still at risk of new outbreaks.

For nearly two months, there had been almost no new cases of coronavirus reported in Beijing. But on Friday, one new case was reported, a number that rose dramatically on