Clinical Characteristics and Outcomes of Patients With SARS-CoV-2 Reinfection

OBJECTIVE: To examine the clinical characteristics, risk of hospitalization, and mortality of patients diagnosed with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection. PATIENTS AND METHODS: We retrospectively reviewed all patients with SARS-CoV-2 reinfection at all Mayo Clinic sites between May 23, 2020, and June 30, 2021 (the period before the emergence of the Delta variant in the United States). The reinfection was defined as a positive SARS-CoV-2 test more than or equal to 90 days after initial infection or 45-89 days after with symptomatic second episode. Vaccination status was classified as fully vaccinated, first dose, and unvaccinated. Comparative analysis of baseline characteristics and comorbidities was performed by hospitalization and vaccination status. The survival analysis of the hospitalized patients was performed using Cox proportional hazard regression. RESULTS: Among the 554 patients reinfected with SARS-CoV-2, 59 (10.6%) were pediatric, and 495 (89.4%) were adults. The median age was 13.9 years (interquartile range, 8.5-16.5 years) for the pediatric and 50.2 years (interquartile range, 28.4-65.6 years) for the adult population. Among the adult patients, the majority were unvaccinated (83.4%, n=413), and the duration to reinfection from initial infection was the longest in the fully vaccinated group (P<.001). Forty-two (75%) out of 56 patients were seropositive within 7 days of reinfection. In hospitalized adult patients, Charlson Comorbidity Index was an independent risk factor for mortality (adjusted hazard ratio, 0.35; 95% CI, 0.19-0.51). CONCLUSION: In this study, most adult patients with SARS-CoV-2 reinfection were unvaccinated. Furthermore, the duration to reinfection was longest in fully vaccinated individuals. Seropositivity was common among adult patients.