The study investigated the risk of re-infection among individuals previously infected with SARS-CoV-2. Patients within a single health system in Ohio and Florida who were tested for COVID-19 between March 12, 2020 and February 24, 2021 were included in the retrospective cohort, regardless of test results. Within individuals, positive SARS-CoV-2 tests prior to August 30, 2020 were considered an initial infection. Following this initial diagnosis, re-infection was defined as an individual’s second positive PCR test from September 1, 2020 onwards.
After 90 days, 1,278 positive patients were retested and 63 were identified as possible reinfections (4.9%). Of these, 31 were symptomatic (49.2%). The average time to reinfection was 138.9 days (range: 90.2 to 294.9 days)