In their contribution to the “Covid-19 and the Social Sciences” series, Larry Au, Zheng Fu and Chuncheng Liu examine how experts and expertise have been drawn upon in predicting the path of the pandemic and how to respond to it in China, Hong Kong, and the United States. The authors draw on their ongoing research that traces media accounts of the role of expert knowledge in all three places, and discuss how different kinds of expertise engage with different audiences: with the state in China, with civil society in Hong Kong, and with both in the United States.