Joshua Weitz, from the University of Maryland, visited our lab last week. Joshua is a mathematical biologist who studies the ecology and evolution of viruses. He gave a fascinating departmental seminar about how viruses may evolve to have intermediate efficiency at exploiting their hosts, and the implications of this for managing disease outbreaks in human populations. He explores related ideas in his latest book Asymptomatic: The Silent Spread of COVID-19 and the Future of Pandemics, published by Johns Hopkins University Press.