Ongoing Excess Hospitalizations for Severe Pediatric Group A Streptococcal Disease

Abstract Objectives A major, Europe-wide outbreak of invasive pediatric Group A streptococcal infections (iGAS) began in late fall 2022. Here we report the evolution of GAS hospitalizations in children and adolescents during the second outbreak year in 2023-2024 at a tertiary care pediatric center in Bern, Switzerland. Methods Ongoing prospective monitoring of all in-patient cases below 16 years of age of GAS infections including those fulfilling the iGAS criteria. We compared case frequencies and clinical characteristics of GAS hospitalizations in 3 periods including the prepandemic years 2013-2020, the first (2022-2023) and the second outbreak year (2023-2024), respectively. In-patient surveillance for respiratory viruses consisted of panel diagnostics in nasopharyngeal specimens of all patients admitted for acute respiratory tract disease. Results Annual GAS hospitalizations increased from a median of 25 case (range 11-28) in 2013-2020 to 89 and 57 cases in the epidemiologic years 2022-2023 and 2023-2024, respectively. iGAS cases evolved similarly (2013-2020, median 4 cases, range 3-8; 2022-2023, 32 cases; 2023-2024, 19 cases). The decline in cases from 2022-2023 to 2023-2024 included all types of GAS organ involvement except complicated suppurative infections in the head area, which remained largely unchanged (48 vs. 42 cases). Pleural empyema and bacteremic pneumonia declined from 13 to 6 cases, possibly explained by a poor overlap of the GAS and influenza curves in 2023-2024 compared to 2022-2023. Conclusion We present evidence for the prolongation of the GAS outbreak into its second winter season in 2023-2024, however with substantial a decline of iGAS, pleural empyema, skin and soft tissue infection and infections of bone, joint and muscle.