Hong Kong flu cases surge as vaccine protection wanes, expert warns

Hong Kong is experiencing a concerning rise in seasonal influenza cases, particularly among children and the elderly, driven by waning vaccine protection according to leading infectious disease expert Professor Ivan Hung Fan-ngai. On Saturday, Hung warned that community immunity has weakened as the seasonal vaccination scheme launched about six months ago, and antibody levels have dropped. He noted a clear upward trend in both influenza A and B infections at Queen Mary Hospital, with more elderly and pediatric patients. The warning follows a severe case of a 17-year-old unvaccinated boy with chronic illnesses who suffered pneumonia and shock from influenza B and remains in critical condition.

Hung attributed the rebound to decreased infection numbers over recent months, which caused antibody levels to fall even in vaccinated individuals. He emphasized the importance of high-risk groups receiving the seasonal flu shot immediately. Health authorities are monitoring whether this uptick will become another full influenza peak. The situation underscores the ongoing challenge of maintaining community protection as vaccine efficacy wanes over time, especially for vulnerable populations like the elderly and children with underlying conditions.