Hong Kong’s flu vaccination rates among most age groups are below the 70 per cent threshold needed for herd immunity even as the winter influenza season approaches, a leading government medical adviser has warned. Professor David Hui Shu-cheong, chairman of the government’s Scientific Committee on Emerging and Zoonotic Diseases, on Saturday reminded the public to get vaccinated ahead of Lunar New Year, when social gatherings are frequent. He noted that 70 to 80 per cent of severe flu cases among...