Is vaccination necessary for COVID-19 patients? A retrospective cohort study investigating reinfection rates and symptomatology in a tertiary hospital.

Background: Durability of immune response by the COVID-19 natural infection and the necessity of vaccines in recovered patients are important inquiries for the healthcare provider.
Research Design and Methods: Here, we investigated the characteristics and the rate of cases with reinfection that have been admitted to our tertiary hospital.
Results: A total of 119985 patients were applied between March 2020 and May 2021. Of these patients, 32607 (27%, 32,607/119985) tested positive. A total of 27 (0.08%, 27/32607) patients were found to be reinfected beyond 90 days. Only one of these reinfected patients (0.003, 1/32607) had novel COVID-19 pneumonia and was hospitalized for the second time. Other 26 reinfected patients were followed up as outpatients.
Conclusions: COVID-19 reinfection is extremely rare. However, the reinfection may be severe in patients with immune deficiency. Healthcare providers may prioritize uninfected and immune-compromised patients for vaccination.