Chen Erzhen — who is vice-president at Ruijin Hospital and a member of Shanghai's COVID-19 expert advisory panel — has estimated that the majority of the city's 25 million people may have already been infected.In other major Chinese cities — including Beijing, Tianjin, Chongqing and Guangzhou — health officials have suggested that the wave has already peaked.Chinese officials brace for travel waveChinese officials are bracing for a virus wave to hit China's under-resourced rural interior, as millions of people prepare to travel back to their home towns for the week-long Lunar New Year public holiday beginning on January 21.In an interview with state broadcaster CCTV, National Health Commission (NHC) official Jiao Yahui admitted that dealing with the expected peak in rural areas would be an "enormous challenge".Countries, including the US, have also cited Beijing's lack of transparency around infection data and the risk of new variants as a reason to restrict travellers."