While medical and public health personnel are working at full speed to anticipate and deal with clinical cases, the work of researchers in bioinformatics (the interdisciplinary research that collects and analyzes genomic data) is just as critically important in responses to COVID-19. It has been possible to extend those techniques to biological materials gathered from archeological sites dating back at least as far in time as the Black Death, and to construct phylogenetic trees for historical plague and syphilis. As a result, we’ve learned more about those long-ago diseases in the last twenty years from bioinformatics than, probably, we did from the entire preceding study of the historical record. COVID-19 will take longer to understand, but our new tools will make this pandemic easier to decipher.