About 0.4 percent of patients who previously tested positive for COVID-19 tested positive again after 90 days, according to Epic Health Research Network data released April 23.
Researchers at the Verona, Wis.-based company analyzed lab test data from 98 healthcare organizations covering 63 million patients. According to the CDC, a positive test within 90 days of initial onset of illness is more likely to represent continued viral shedding than reinfection, so researchers focused on results after 90 days.
Epic data found 396,883 patients who had at least one positive result, and 37,489 patients who had two or more positive test results during the study. Only 0.4 percent of the patients, or 1,601 patients, had a subsequent positive test at least 90 days after their initial positive test, indicating possible reinfection.
Of the 1,601 patients, 496 (31 percent) were admitted to the hospital within 21 days of their most recent positive test and 54 (3.4 percent) died within 21 days of their most recent positive test. The researchers believe the COVID-19 patients with hospital admissions or deaths may be more likely to represent true reinfections.
Subsequent positive COVID-19 tests could be due to residual shedding, actual reinfection or other reasons that require more analysis. The Epic findings do not consider genomic sequencing data.