Unvaccinated children and elderly people are four to five times more likely to face serious complications or mortality from flu infections than those who receive vaccinations, a Hong Kong health official has warned, as influenza cases in the city continued to rise. Director of Health Ronald Lam Man-kin issued the warning on Saturday as he pointed out that Hong Kong’s influenza infections had been increasing since June. “Up until last week, the number of flu infections still remained at a high...