Abstract
The proportion of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections diagnosed by coronavirus disease 2019 (COVID-19) tests, including home antigen tests, is unknown. We detected infections among blood donors in the United States (US) by testing for nucleocapsid antibody (anti-N) seroconversion and administered a questionnaire to determine the proportion of those infections that were associated with a self-reported positive COVID-19 test. Among US blood donors with serologic evidence of SARS-CoV-2 infection who completed a survey, 47.7% reported an associated self-reported positive COVID-19 test. This proportion changed from July-December 2020 (44.9%) to July-December 2022 (54.8%). This study suggests many SARS-CoV-2 infections in adults are not diagnosed with a test.