Several top Chinese scientists have called for hypervigilance against the possible collision of Covid-19 and influenza outbreaks this winter as coronavirus cases again rise in some major cities. Speaking at the World Flu Day symposium on Monday, Zhong Nanshan , China’s top respiratory expert, warned that the risk of the respiratory disease double whammy was high around the world, China’s official Science and Technology Daily outlet reported. China faces surging Covid-19 cases in many parts of the country as winter approaches. On Tuesday, there were 409 new local symptomatic cases and 2,346 new local asymptomatic cases. Outbreaks were found in more than a dozen provinces and municipalities. Some local governments have called for extreme caution over both influenza and Covid-19. Health authorities in the southern city of Guangzhou said they faced a “dire and complicated” outbreak this week, recording more than 500 infections in the past week. On Wednesday, Zhengzhou in central Henan province slapped a seven-day lockdown on the entire district where the main Foxconn plant is located. The province has been in the limelight after an exodus of workers from the Covid-hit plant, the largest iPhone manufacturer in the world, caused a commotion on social media at the weekend. Henan governor Wang Kai told a conference on Monday the province had to prepare in case of large outbreaks this winter and spring. While holding fast to its zero-Covid restrictions, China is also keeping a watchful eye on spikes in coronavirus cases and other respiratory diseases elsewhere around the globe. The long-term toll of living under China’s long zero-Covid shadow There are worrying signs that influenza cases are rising in some countries. In the United States, the flu season arrived a month earlier than usual and it has already driven a significant jump in hospital admissions. America’s Centres for Disease Control and Prevention estimates there have been at least 880,000 illnesses recorded, nearly 7,000 hospital admissions and 360 deaths from the flu this season. So far, there has not been a fresh surge in illness or mortality from Covid-19 in the US but scientists remain concerned as winter approaches. Last month, Germany reinstated the mask mandate for some public transport amid a surge in cases, although case numbers have stabilised this week. Britain also saw an early arrival of influenza season, although the Covid-19 infection level remains steady. However, an uptick in Britain and the US of the respiratory disease RSV among children has prompted worries among some experts about the possibility of a “tridemic”. Former chief of the Chinese Centre for Disease Control and Prevention (CDC), George Gao Fu, told the World Flu Day symposium on Tuesday that the rise in influenza cases might be related to weakened immunity because of public health measures over the past three years. And the relaxation of social distancing rules in many countries had furthered the rise of new influenza strains. He also attributed the spread of influenza to low rates of vaccination against the flu. Zhang Wenqing, director of the World Health Organization’s Global Influenza Programme, told the symposium there had been a surge in influenza cases in the southern hemisphere winter this year and it was important to look out for a high incidence during the northern hemisphere winter. Australia recorded its worst influenza outbreak in years, with 252 deaths between January and July. But the pandemic remains far deadlier, with more than 6,600 Covid-19 deaths in the country over the same period. No end in sight for China’s zero-Covid policy with experts left at a loss A higher number of influenza cases recorded in Australia may be attributed to better surveillance in the pandemic era. Still, some experts are concerned it may be a harbinger for the northern hemisphere of parallel flu and Covid-19 outbreaks. As more people gather indoors during colder weather, the risk of respiratory diseases spreading rises. In the same forum, Gao also warned of a heightened risk of bird flu H5N1 as large-scale animal outbreaks are reported in Europe and the US, bringing with them the chance of spilling over into humans.