In response to the evolving COVID-19 pandemic, particularly in the area of data analytics, Mathematica created a COVID-19 Data Primer. The primer is designed to help researchers, data scientists, and others who analyze health care claims or administrative data quickly join the effort to better understand, track, and contain COVID-19. Today, Mathematica launched an update adding information on linking claims to public data sources and information on how diagnosis and procedure codes are being used in claims.