COVID-19 Relapse and Reinfection Frequency, Clinical Features of Cases

Abstract

Purpose: How the immune response of people infected with SARS-CoV-2 develops against the virus and how long it is effective is one of the most important questions during the pandemic period. We aimed to examine the frequency of relapse and re-infection, examine the influencing factors, evaluate the cases' clinical conditions and symptoms, and examine the severity of subsequent infection.
 Materials and Methods: This is a descriptive and cross-sectional type study using the Public Health Management System (PHMS) records of the Turkish Ministry of Health. Clinical improvement and negative RT-PCR test results, and positive RT-PCR test results at least 45 days after the first infection were included in this study. The cases were divided into two groups: the relapse group, those positive for 45-89 days after the first infection, and the reinfection group after 90 days recommended by the CDC. Demographic characteristics, whether or not to be a health worker, accompanying chronic illness, and re-positivity periods were evaluated.
 Results: The total number of cases was 103,096. The number of cases with repeat positivity detected after 45 days was 78. In the study, the number of cases in the relapse group (45-89 days) was 49, while the number of cases in the reinfection group (over 90 days) was 29.
 Conclusions: The very low rate of reinfection and milder symptoms in the second infection are promising for vaccination studies. Understanding the COVID-19 reinfection could be the key to guiding government and public health decisions in the coming months.