What’s behind China’s recent spike in Covid-19 cases? And is it anything to worry about?

China has seen a spike in Covid-19 in recent weeks, overtaking influenza as the top respiratory pathogen for the first time this year, but most patients experienced mild symptoms, while the medical authorities said data suggested the infection rate was significantly lower than last year’s peak. The spread of the Omicron NB.1.8.1 variant has reached a “moderate transmission level”, according to the Chinese Centre for Disease Control and Prevention (CDC). The CDC does not give a weekly total of...