A pandemic control expert who has been a key government adviser during the Covid-19 crisis will step down as head of a top Hong Kong university’s public health school by the end of next year after his contract was not renewed, sources have confirmed.A source close to the school said the decision was made last week, four years after the 65-year-old professor, Keiji Fukuda, joined the school of public health at the University of Hong Kong on a contract-based arrangement in 2016. He was promoted…