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 new infections, but its most recent data – covering the week of July 13-19 – showed the positive rate for Covid-19 tests had reached 16.3 per cent, an increase of 4.3 percentage points compared with the previous week. Meanwhile, the positive rate for influenza was 12.6 per cent, a fall of 0.9 points.