On Jul. 31, 2020, Yale researchers reported that differing immune system responses of patients with COVID-19 can help predict who will experience moderate and severe consequences of disease. The study was published in the journal Nature.

They found that all patients shared a common COVID-19 ﾓsignatureﾔ in immune system activity early in the course of disease. But those who experienced only moderate symptoms exhibited diminishing immune system responses and viral load over time.