Increasing incidence and severity of invasive Group A streptococcal disease in Spanish children in 2019–2022

On December 2022, an alert reporting an unusual increase in Group A Streptococcus (GAS) non-invasive (mainly tonsillitis and scarlet fever) and invasive GAS disease (iGAS) was published in the UK. Several deaths in children under ten years old in a short period have been reported, up to 24 in UK.^1,2 Other European countries have also reported similar concerns of increased GAS infections.³

PedGAS-net is a Spanish multicenter network for studying iGAS in patients ≤16 years old. We have analyzed the epidemiology, manifestations, and outcomes of children with iGAS between January 1, 2019, and December 31, 2022, in 24 hospitals from PedGAS-net aiming to describe changes in the incidence and severity (additional methodological information in Supplementary Appendixes S1–S4).

Two hundred and twenty children with iGAS were evaluated (characteristics in Supplementary Table S2). The median age was 41.2 months (IQR:19.3–81.0). Eighty-nine (40.5%) children required intensive care admission. The most common syndromes were pneumonia (n = 66, 29.6%; 42/66 complicated with pleural effusion), followed by skin and soft tissue infection (n = 50, 22.7%), osteoarticular infection (n = 27, 12.3%) and primary bloodstream infection (n = 23, 10.5%). Furthermore, twenty-five (11.4%) and ten (4.5%) children developed streptococcal toxic shock syndrome and necrotizing fasciitis, respectively. The average annual incidence rate of iGAS was 5.96 episodes/100,000 children attended at the emergency department/year, showing a considerable decrease during the COVID-19 pandemic, with its nadir in 2021.

Comparing iGAS episodes in 2019 (pre-COVID-19 pandemic) versus 2022 (post-COVID-19 pandemic) (Supplementary Table S2), we found an impressive rise of cases between November and December 2022, coinciding with the alert reported in other countries. Thus, in December 2022, there was an almost 4-fold increased incidence compared to those months with the highest number of cases in 2019 (Fig. 1). Remarkably, this increased incidence of iGAS coincided with the weeks with the highest respiratory syncytial virus (RSV) circulation. Additionally, after comparing several syndromes, complications and outcomes (Supplementary Table S2) we observed intensive care admissions and pneumonia diagnoses were more frequent in 2022 compared to 2019 (48.6% vs. 30.4%, p = 0.013, and 36.2% vs. 22.8%, p = 0.050, respectively). Four patients (1.8%) died within the study period; three of them in December 2022.

Fig. 1.

Monthly distribution of invasive Streptococcal Group A disease in children between 2019 and 2022. The red lines indicate remarkable changes in public health measures to prevent SARS-CoV-2 transmission. The blue shaded area indicates respiratory syncytial virus epidemics in Spain.

In summary, compared to the pre-pandemic COVID-19 period, we have observed a significant increase in the severity and number of iGAS cases in Spain in 2022, sharply clustered in the last months. We have seen an increase in pneumonia cases, which may be related to the temporal coincidence with the highly intense RSV and influenza seasons we have experienced.⁴ These respiratory viral epidemics could explain this situation along with a lack of exposure to pathogens suffered by children due to their social isolation during the pandemic.⁵ However, an analysis of the GAS strains will be carried out in the coming months to rule out the circulation of more invasive emerging strains.

Contributors

EC-V, DA-A, CC, and JS-L conceptualized and designed the study. EC-V and DA-A performed the data management. EC-V, DA-A, CC, and JS-L drafted the manuscript. All authors enrolled participants and participated in the collection of data. All authors were involved in the preparation and review of the final manuscript. All authors participated and were involved in the critical review of the final manuscript.

Declaration of interests

The authors have no conflicts of interest relevant to this article to disclose.