Beijing and Shanghai both resumed mass testing for Covid-19 as new community outbreaks of the virus emerged just days after the two key Chinese cities eased social curbs that had been in place for months. The capital restarted screening for the virus in several neighborhoods of the Chaoyang district, where many company headquarters and embassies are based, after a flareup in a local bar ended a five-day streak of zero community spread on Thursday. Shanghai briefly locked down most of the city Saturday to undertake mass testing as authorities continue to report Covid cases outside of quarantine areas. The quick escalation adds to concerns that China’s Covid Zero strategy may send cities into repeated lockdowns and re-openings given the high transmissibility […]