Across the United States, there were 95 235 reported deaths officially attributed to COVID-19 from March 1 to May 30, 2020. In comparison, there were an estimated 122 300 (95% prediction interval, 116 800-127 000) excess deaths during the same period (Table). The deaths officially attributed to COVID-19 accounted for 78% of the excess all-cause deaths, leaving 22% unattributed to COVID-19. The proportion of excess deaths that were attributed to COVID-19 varied between states and increased over time (Table and Figure 1).
Figure 1: Excess Deaths in the United States From March 1 Through May 30, 2020. The observed number of deaths is indicated by the solid line, and the expected number of deaths, adjusting for seasonality, influenza epidemics, and reporting delays, is indicated by the dashed line. The area between these 2 lines represents the total number of excess deaths: blue-gray (bottom), deaths recorded as due to COVID-19; orange (narrow middle section), additional pneumonia and influenza excess deaths not coded as due to COVID-19; and beige (top), deaths that were not attributed to COVID-19, pneumonia, or influenza.
This implies a point estimate for undercount of Covid-19 fatalities by 27,000 for the March-May period.
(This approach is not persuasive if you thought the excess deaths were primarily people who were going to die in the very near future; for examples, see the excess fatalities debate for Puerto Rico/Hurricane Maria.)