Variations in the frequency of streptococcal tonsillopharyngitis among children after COVID-19

Abstract

Aim: Comprehensive data on the variations in the frequency of Streptococcus pyogenes (GAS) tonsillopharyngitis before
 and after the Coronavirus disease 2019 (COVID-19) pandemic are still insufficient. This study aimed to investigate the changes in the frequency of GAS in children before, during, and after the COVID-19 period.
 Material and Methods: This retrospective study included 13,061 patients diagnosed with a pre-diagnosis of bacterial tonsillopharyngitis based on clinical findings, between June 2018 and June 2023. All patients were administered the Strep A antigen test, and throat swab samples were collected. Patients were divided into three groups based on their hospital admission dates. Group 1, pre-COVID-19 pandemic period (1 January 2018 – 10 March 2020); Group 2, during the COVID-19 pandemic when strict measures were enforced (11 March 2020 – 30 June 2021); and Group 3, the period after the lifting of COVID-19 pandemic measures (1 July 2021 – 30 June 2023).
 Results: The prevalence of GAS in the entire population was 23.2% (n=3024). Among the groups, Group 3 had the highest ratio of GAS cases, followed by Group 1, and then Group 2 (Group 1: 18.1%, Group 2: 6.0%, Group 3: 29.6%, p < 0.001). During the period characterized by stringent measures against the COVID-19 pandemic, a significant reduction in the frequency of GAS was observed in comparison to the pre-COVID-19 era. However, with the relaxation of COVID-19-related restrictions, particularly in the last quarter of 2022 and the spring of 2023, there was a marked increase in the frequency of GAS. Conclusion: In children, the frequency of GAS significantly decreases with COVID-19 isolation measures. However, a rebound increase is observed following the relaxation of these isolation measures.