A retrospective cross-sectional observational study of SARS-CoV-2 reinfection in La Ribera Health Department, Valencia, Spain

Abstract

Introduction. The possibility of reinfection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a widely proven fact and may have clinical implications. Hypothesis /Gap Statement. It is not known whether there have been cases of reinfection by SARS-CoV-2 in La Ribera Health Department. Aim. To determine whether there have been cases of reinfection by SARS-CoV-2 in La Ribera Health Department and to identify their characteristics. Methodology. Retrospective cross-sectional observational study of cases of reinfection by SARS-CoV-2 in the population of La Ribera Department between March 2020 and February 2021. The positive baseline cohort includes all cases positive by RT-PCR for SARS-CoV-2, with reinfection cases being those that, after resolution of the first episode according to the World Health Organization (WHO) criteria, presented a new positive RT-PCR result. Results. Out of a total of 15 687 cases with positive RT-PCR, 40 were considered to be reinfections, which meant a cumulative incidence of 0.255 % and an incidence density of 5.05 cases per 100 000 person-days. Most of the cases occurred during the highest incidence peaks of the pandemic in the department. Seventy-five per cent of the patients in these cases were older than 40 years, 42.5 % were healthcare professionals or nursing home residents and 12.5 % had an immunosuppressive comorbidity. There were no severe, critical or death cases. In the reinfection episodes, with respect to the first episode, there was a tendency to be milder, they required fewer days of hospitalization, their RT-PCR became negative earlier, they developed a greater humoral response and the sick leave period was shorter. The median period between the RT-PCR in the first episode and the RT-PCR in the second episode was 127.5 days (range: 48–301; IQR: 89.5–256.25) Conclusions. SARS-CoV-2 reinfection cases are rare, tend to be mild and can occur within a median period of 127.5 days.