The ongoing epidemic of coronavirus disease 2019 (COVID-19) is devastating, despite extensive implementation of control measures. The outbreak was sparked in Wuhan, the capital city of Hubei province in China, and quickly spread to different regions of Hubei and across all other Chinese provinces.

As recorded by the Chinese Center for Disease Control and Prevention (China CDC), by Feb 16, 2020, there had been 70 641 confirmed cases and 1772 deaths due to COVID-19, with an average mortality of about 2·5%.¹ However, in-depth analysis of these data show clear disparities in mortality rates between Wuhan (>3%), different regions of Hubei (about 2·9% on average), and across the other provinces of China (about 0·7% on average). We postulate that this is likely to be related to the rapid escalation in the number of infections around the epicentre of the outbreak, which has resulted in an insufficiency of health-care resources, thereby negatively affecting patient outcomes in Hubei, while this has not yet been the situation for the other parts of China (figure A, B). If we assume that average levels of health care are similar throughout China, higher numbers of infections in a given population can be considered an indirect indicator of a heavier health-care burden. Plotting mortality against the incidence of COVID-19 (cumulative number of confirmed cases since the start of the outbreak, per 10 000 population) showed a significant positive correlation (figure C), suggesting that mortality is correlated with health-care burden.