The battle against coronavirus disease 2019 (COVID-19) only begins with a test to identify who is infected and who is not. To accelerate an effective response, we have to move beyond the initial diagnosis to prognosis: Who is most susceptible to developing serious, life-threatening symptoms? Currently, there is no way to tell whether an infected individual (or an individual who may become infected) will be asymptomatic or require hospitalization. This wide variation in disease severity is, at least in part, a reflection of the myriad changes that occur within a person’s body as it fights the virus, which in turn reflect the unique biological makeup of that individual.
