David, who is in his forties and works in finance in Hong Kong, does not remember a life without hepatitis B, a viral infection of the liver. “I have been a … carrier for as long as I can remember,” he says. “I found out early on as a child since I was born with it – my mother is a carrier, too.” David’s experience is far from unusual in Hong Kong. According to Dr Loey Mak Lung-yi, a specialist in gastroenterology and hepatology, mother-to-child transmissions account for more than 90 per cent of...