Flu wave may drag on if dominant strain shifts to H1N1, health expert warns

Hong Kong’s influenza activity has yet to peak and the outbreak could be prolonged if the dominant strain shifts, respiratory medicine expert David Hui Shu-cheong warned.

Speaking on a television program on Sunday, Hui, a professor of respiratory medicine at the Chinese University of Hong Kong, said several key outbreak indicators and sewage surveillance data showed that flu activity remained high.

He said H3N2 remained the dominant strain, but the proportion of H1N1 cases had risen to nearly 40 percent. As the local population has relatively limited immunity against H1N1 after a long period without a major wave, Hui warned that the surge could be extended if H1N1 became the dominant strain.

On Covid-19, Hui said the Omicron subvariant NB.1.8.1 remained the main circulating strain, adding that the summer wave could last about three months.

However, he said hospitalization and mortality rates had fallen due to “hybrid immunity” built up through previous infections and vaccination. Symptoms are generally mild, though unvaccinated elderly people and patients with chronic illnesses remain at higher risk.

With existing vaccine stocks set to expire before a new batch arrives in the fourth quarter, Hui advised high-risk groups to wear masks in crowded places during the interim period.

For office workers who contract Covid-19, he said they could return to work while wearing a mask once their fever had subsided and their cough was mild.

Asked about Ebola outbreaks in parts of Africa, Hui said border health measures at the airport remained robust. Health authorities are monitoring travelers arriving from high-risk regions for 21 days, and no cases have been detected in Hong Kong so far.

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