The U.S. healthcare delivery system is accustomed to seasonal variation in the demand for acute care related to infection from influenza viruses. Yet reported hospitalizations and deaths likely associated with influenza for the 2020-21 season are well below estimates of even the mildest of prior periods. We analyzed Milliman MedInsight’s Emerging Experience research dataset, and found that influenza office visit, emergency department, and hospital inpatient utilization rates were significantly lower in 2020 by 94% than the previous year, and 86% versus 2018. In this brief, we discuss three hypotheses to explain the steep declines.