As Dr. Brian Garibaldi directed the Johns Hopkins Biocontainment Unit in Baltimore amid COVID-19, a fit, active man in his 30s struggled on a ventilator for 40 days. Meanwhile, a 117-year-old French nun contracted the disease, fully recovered and didn’t even know she had it. To explain this shocking difference, Garibaldi and Johns Hopkins Applied Physics Laboratory researchers Will Gray Roncal and Karla Gray Roncal leveraged big data and machine learning to unravel the mystery of the different reactions, predict patients’ probable disease course and identify unique treatment needs. Garibaldi, Will Gray Roncal and Karla Gray Roncal will discuss how big data and machine learning advanced precision medicine for COVID-19 and how the techniques could be applied to other diseases.