Background: Vaccination is a highly effective strategy for the prevention of enterovirus A71 (EV-A71)—hand, foot, and mouth disease (HFMD). Three inactivated EV-A71 vaccines in China have demonstrated remarkable efficacy against EV-A71-HFMD during clinical trials, exhibiting vaccine effectiveness (VE) exceeding 90% and few adverse events (AEs). However, the effectiveness of vaccines in the real world and its impact on the epidemiological characteristics of HFMD after the use of EV-A71 inactivated vaccine are uncertain. Methods: The odd ratio (OR) and 95% confidence (CI) were used as the effect estimates of the meta-analysis in the test-negative design (TND), and the OR was used to calculate VE: VE = (1 − OR) × 100%. Results: According to the literature search strategy, a comprehensive search was conducted in PubMed, Web of Science (including Chinese Science Citation Database and MEDLINE), and Embase, and 18 records were ultimately included in this study. Subsequently, the overall VE and 95% CI of different vaccine doses were analyzed, with the one-dose vaccine at 66.9% (95% CI: 45.2–80.0%) and the two-dose vaccine at 84.2% (95% CI: 79.4–87.9%). Additionally, the most reported AEs were mild general reactions without any rare occurrences. Simultaneously, the widespread use of the EV-A71 vaccine would lead to a reduction in both the incidence of EV-A71-associated HFMD and severe cases caused by EV-A71. Conclusion: The administration of the two-dose EV-A71 vaccine is highly effective in preventing HFMD in the real world, and the widespread use of the EV-A71 vaccine leads to a reduction in the incidence of EV-A71-associated HFMD and that of severe cases caused by EV-A71. The findings suggest that administering the two-dose EV-A71 inactivated vaccine to children aged 6 months to 71 months can be effective in preventing EV-A71-associated HFMD, highlighting the need for developing a multivalent HFMD vaccine for preventing cases not caused by EV-A71.

Hand, Foot, and Mouth Disease (HFMD) is an infectious disease caused by enteroviruses (EVs) and is extremely contagious and prevalent among infants and children under 5 years old

Background: The post–coronavirus disease 2019 (COVID-19) pandemic resurgence of Mycoplasma pneumoniae (MP) infections, particularly in China, underscores the need to understand the drivers of disease severity.Purpose: This study aimed to evaluate the association between predominantly circulating MP strains and disease severity in Henan Province, central China.Methods: We integrated the clinical data of 3,060 pediatric patients and analyzed the epidemiological characteristics of MP pneumonia (MPP) in the Henan region in 2020–2024. Bronchoalveolar lavage fluid collected from 137 patients was analyzed using multilocus sequence typing and multilocus variable number tandem-repeat analysis to investigate the correlation between genotype and clinical outcome.Results: A significant post-COVID MPP outbreak was predicted in 2023. Genotyping revealed the cocirculation of 2 major genotypes: the prevalent ST3 (57.7%, severe ratio [31.6%]) and the less common but highly virulent ST14 (26.3%, severe ratio [72.2%]). Phylogenetic clustering confirmed ST14/3-5-6-2 as part of a broader hypervirulent lineage, common cluster label 14 (CCL14), which was significantly associated with disease severity (χ2=19.39; P<0.001). Patients infected with CCL14 strains exhibited a distinct hyperinflammatory profile marked by elevated D-dimer levels, complement C4 levels, and platelet count. The mutation ratio of macrolide resistance sites in the MP strains from Henan Province was approximately 75%.Conclusion: Our findings identified the CCL14 lineage as a key driver of disease severity in macrolide-resistant pediatric MPP in Henan Province, China. This under scores the importance of integrating molecular surveillance with clinical monitoring to mitigate disease burden.