In the coastal Chinese city of Xiamen, it’s not just the mouths of fishers being swabbed for Covid-19, but also the fish they’ve caught. As China maintains its commitment to zero Covid, city authorities are working to ensure there is no avenue for the virus to enter, ordering all fishers and their catch undergo a daily nucleic acid test. According to the Xiamen Jimei district’s political and legal committee, it was necessary to swab both returning workers and their “materials” immediately upon disembarking each day, because some fishers had made illegal trades or contact with overseas vessels while at sea,...