The covid-19 pandemic has exposed failures to respond effectively to the emergence of a highly contagious and lethal microbial threat. Covid-19, however, is not the first pandemic this century due to an emergent pathogen and is unlikely to be the last. Over the past 20 years a number of high impact pathogens have emerged or re-emerged, such as three new coronaviruses—namely, severe acute respiratory syndrome (SARS) in 2003; Middle East respiratory syndrome (MERS) in 2012; and the current covid-19 pandemic (SARS-CoV-2). We have also seen several highly pathogenic influenza A viruses (eg, H5N1 in 2003; H7N9 in 2013; and the H1N1 pandemic in 2009), the Zika virus in 2016, and the continuing rise and spread of Ebola in West and Central Africa since 2013. All these pathogens have jumped from transmission among non-human animals to transmission among humans. During this century, the frequency of epidemics and pandemics might continue to increase, driven mainly by demographic trends, such as urbanisation, environmental degradation, climate change, persistent social and economic inequalities, and globalised trade and travel.