Flu cases are rising in Hong Kong, particularly among children and the elderly, as waning vaccine protection weakens community immunity, a leading infectious disease expert has warned.
Professor Ivan Hung Fan-ngai, chair professor of infectious diseases at the University of Hong Kong, made the warning on Saturday and urged high-risk groups who had not yet received a seasonal flu jab to get one.
The remarks came a day after health authorities said an influenza B infection had left a 17-year-old boy with chronic illnesses suffering from severe pneumonia and shock. The teenager, who was not vaccinated, is in a critical condition.
Hung told a radio programme that flu infections had rebounded since January after an earlier decline.
“There has indeed been an upwards trend recently in the number of flu infections for both Influenza A and B. For example, at Queen Mary Hospital, we’ve witnessed more flu infections among the elderly and children,” he said. “But we need to wait and see to decide if the trend is another influenza peak.”
Hung attributed the rise to weakened community immunity as vaccine protection declined over time.
“The seasonal influenza vaccination scheme has been under way for about half a year, and the immunity of most vaccinated individuals has begun to decline. As the number of infection cases has decreased over the past few months, their antibody levels also dropped,” he said.