CDC COVID-19 Science Update released September 22, 2020 – “Key Findings:

• By April 18, 2020, the estimated cumulative SARS-CoV-2 incidence in the US was ~2%.
  • The number of estimated cumulative SARS-CoV-2 infections was 8.6 times the number of confirmed infections: 6,454,951 vs 751,245.
  • 84% of the difference between estimated cumulative and reported confirmed cases was due to incomplete testing and 16% was due to test inaccuracy.
• The estimated cumulative infection rate (range: 3.1 to 65.0/1,000) and ratio of estimated cumulative to reported confirmed SARS-CoV-2 infections (range: 5 to 33) varied widely by state (Figure).
  • Differences among states were driven by different transmission rates, testing rates, and test positivity rates in each state rather than modeling assumptions.

Methods: Analysis using data from the COVID Tracking Project to assess estimated cumulative SARS-CoV-2 infections by state and evaluate contributions of incomplete testing and imperfect test performance…

Implications: Estimated cumulative SARS-CoV-2 infections were greater than confirmed reported infections, due in part possibly to challenges with testing. Monitoring underestimation of reported confirmed cases can provide more accurate estimates of the cumulative burden of SARS-CoV-2 infection…”