ABSTRACT
Background. COVID-19 reinfection is generally defined as having 2 positive SARS-CoV-2 tests greater than 90 days apart. The clinical implications and impact of COVID-19 reinfection are not completely understood. We evaluated clinical and demographic characteristics of patients with COVID-19 reinfection. Methods. All SARS-CoV-2 polymerase chain reaction (PCR) tests performed at Joint Base San Antonio (JBSA), from March 27, 2020 through January 19, 2022 were analyzed. COVID-19 reinfection was defined as having 2 positive PCR tests >90 days apart. Available data for comorbidities, travel, COVID-19 vaccination status, SARS-CoV-2 genotype, symptoms, hospitalization, and treatments were compared for first and second infections. Results. A total of 310,704 SARS-CoV-2 PCR tests performed of which 25,543 (8.2%) were positive at JBSA during the study period. Patients with COVID-19 reinfection (n=532;4.2%) were identified and 266 (50%) charts reviewed. The mean age was 36.5 (+/-15) years and approximately half were males and active duty members (Table 1). The median time from first to second infection was 326 days (IQR 160-385). Patients were predominantly unvaccinated (91.4%) at initial infection, however unvaccinated status was less common (40.2%) at second infection (40.2%;P<0.0001).A significantly higher proportion of patients were symptomatic at first infection (88.3%) compared to second infection (51.5%;P< 0.001). Pneumonia diagnosis was significantly higher (4.9% vs. 0.4%;P=0.0011) whereas hospitalization was similar (2.6% vs. 2.3%;P=0.0788) for first compared to second infection. Among hospitalized patients, critical illness was common for first infection (57.1%) but none of the patients were critically ill with their second infection. A third episode of infection was rarely observed (1.5%). Of 80 genotype samples available, 14 (30%) were paired samples. Among all paired samples different genotypes were responsible for reinfection (Table 2). Conclusion. Patients with COVID-19 reinfections were less likely to be symptomatic, had lower severity of illness, and typically had a different SARS-CoV-2 genotype at second infection. Reinfection occurred despite COVID-19 vaccination in many patients, which highlights the need to develop novel strategies for vaccination.