The incidence of invasive Group A streptococcal infection in children, which plunged during the COVID-19 pandemic control period, has recovered to pre-pandemic levels, a study found.
According to Seoul National University Bundang Hospital on the 18th, a domestic multi-center research team led by professors Lee Hyun-ju and Kim Ye-kyung of the pediatric infectious diseases division announced the results of a Korea Disease Control and Prevention Agency policy project that analyzed 454 patients with invasive Group A streptococcal infection at 23 university hospitals nationwide from 2015 to 2024.
The study was conducted as Korea's largest multi-center research, comprehensively analyzing the 10-year incidence trends, clinical characteristics, and distribution of major genotypes of invasive Group A streptococcal infection in the country.
Group A streptococcus is a bacterium that primarily infects through the respiratory tract or skin soft tissue, causing pharyngitis with a swollen throat and fever, scarlet fever, and skin infections. Among these, invasive Group A streptococcal infection, which has a high fatality rate, refers to cases where the bacteria penetrate the blood, joint fluid, or cerebrospinal fluid. It requires caution as it can rapidly worsen into sepsis or necrotizing fasciitis, or lead to toxic shock syndrome, a fatal complication in which blood pressure drops and multiple organs are damaged simultaneously.
The research team's analysis found that the most notable change over the past 10 years was the rebound in incidence among children and adolescents after the pandemic. The incidence of invasive Group A streptococcus among all pediatric inpatients fell about 90% from 9.34 cases per 100,000 people before COVID-19 to 0.95 cases during the pandemic control period (2020-2022). However, it then rose again to 10.45 cases in 2023-2024. Among adults, the figure decreased from 6.57 to 1.83 cases over the same period, then increased only to 2.47 cases.
For the elderly, the severity burden was greater than the frequency. The mortality rate among those aged 65 and older was 26.5%, far exceeding the average mortality rate (15.5%) and the pediatric mortality rate (10.5%). One in five invasive infection patients (19.6%) progressed to toxic shock syndrome, and in these cases the mortality rate was confirmed at 52.8%.
According to the study, the M1UK lineage spreading overseas was reported in Korea for the first time. The research team said, "This demonstrates the need for a national-level surveillance system that tracks not only the number of invasive Group A streptococcal infection cases but also the severity and genetic changes in the bacterial strains." This means a more thorough surveillance system must be established to detect early signs of increasing infections in specific age groups or regions and the introduction and spread of new lineages such as M1UK.
Professor Kim Ye-kyung, the first author, said, "It is significant that we analyzed the 10-year incidence patterns and clinical characteristics of invasive Group A streptococcal infection on a nationwide basis for the first time in Korea." She added, "In particular, since infections have increased significantly among pediatric patients after the pandemic and the M1UK lineage has also been confirmed in Korea, continuous monitoring of future changes in epidemic patterns is needed."
Professor Lee Hyun-ju, the corresponding author, said, "Group A streptococcus is a commonly encountered bacterium, so awareness tends to be low, but when it manifests invasively, even previously healthy people can deteriorate rapidly within a short time." She added, "Discussions are needed to establish a more proactive surveillance system, such as registering invasive Group A streptococcal infection as a legally designated infectious disease."
