Alliance for Pandemic Preparedness

March 16, 2021

Reinfection Rates among Patients Who Previously Tested Positive for COVID-19: A Retrospective Cohort Study

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  • Previous SARS-COV-2 infection was associated with a lower likelihood of subsequent reinfection compared to those without a previous history of infection. These results are based on a cohort study of over 150,000 patients from a multi-hospital system in Ohio and Florida. Among 8,845 initially PCR-positive patients, 1,278 were retested after ≥90 days and 62 (0.4%) had reinfection (CDC definition of reinfection is a positive test ≥90 days after initial positive test). Of 141,480 initially PCR-negative patients, 39,487 were retested after ≥90 days and 3,191 (2.3%) had positive results. [EDITORIAL NOTE: This analysis relies on medical records of SARS-CoV-2 PCR testing and does not represent a random sample of people with and without prior SARS-CoV-2 infection. Differences between those who do and do not retest for SARS-CoV-2 after an initial positive or negative test result could greatly affect the observed test positivity. Conclusions based on these findings about the effectiveness of prior infection against re-infection should be made with great caution.] 

Sheehan et al. (Mar 15, 2021). Reinfection Rates among Patients Who Previously Tested Positive for COVID-19: A Retrospective Cohort Study. Clinical Infectious Diseases. https://doi.org/10.1093/cid/ciab234