Flu vaccination rates lag in Hong Kong as winter peak nears, expert warns

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 both adults and children during the recent summer season involved unvaccinated patients.

“If the rate of respiratory samples testing positive for influenza, institutional outbreaks and hospitalisation rates continue to rise over the next two weeks, then we will be in the winter flu season,” the respiratory disease expert told a radio programme.

Hui said it would be difficult to predict how long the flu season would last, adding that Hong Kong could be affected by different strains of influenza one after another.

He noted that the city was first hit by H3N2 and then quickly followed by H1N1 for several months in 2023 and 2024.

Hui said the rate of respiratory samples testing positive for influenza had risen from 3.9 per cent the week before to 4.6 per cent last week, edging very close to the baseline of 4.94 per cent.