The COVID-19 Data Index collects and indexes COVID-19 datasets from major data repositories, publications, and individual online sources. Diverse types of datasets, including clinical, epidemiological, imaging, omics, socio-demographic, environment, and transportation data are being generated on a daily basis in response to the COVID-19 pandemic, and the goal of the COVID-19 Data Index is to make these datasets easily findable and reusable for researchers.