Hong Kong officials will be looking closely for cases of unknown origin as the most critical signal of a potential start of a fourth wave of Covid-19 infection in the city, according to Dr David Hui, a close adviser to Hong Kong Chief Executive Carrie Lam and director of the Stanley Ho Centre for Emerging Infectious Diseases. In an interview with the South China Morning Post’s Elaine Ly on October 19, 2020, Dr Hui also said Hong Kong people should expect social-distancing measures to be needed…