The mandatory use of Hong Kong’s [Covid](tag?_=covid) -19 contact-tracing app at local restaurants from December 9 is likely to come with exemptions for children and the elderly, many of whom do not own smartphones, the city’s health chief and an industry leader have indicated. Secretary for Food and Health Sophia Chan Siu-chee on Saturday said the government understood that some members of the public would need help to use the “Leave Home Safe” risk-exposure app when entering venues. Asked by reporters whether children and elderly residents who did not own a smartphone would be exempted from the mandate, Chan replied:…