China battles worst Covid outbreak for two years as cases double in 24 hours

China reported nearly 3,400 daily Covid-19 cases on Sunday, double the previous day, forcing lockdowns on virus hotspots as the country contends with its gravest outbreak in two yearsA nationwide surge in cases has seen authorities close schools in Shanghai and lock down several north-eastern cities, as almost 19 provinces battle clusters of the Omicron and Delta variants.The city of Jilin has