Human adenoviruses (HAdVs) are significant viral pathogens associated with a wide spectrum of diseases, particularly acute respiratory tract infections (ARTIs) in children. This study aimed to characterize the epidemiological features of HAdV infections among hospitalized pediatric patients in Hainan Province, China, from January 2021 to December 2024, encompassing the COVID-19 pandemic and post-policy transition period. Among 31,843 hospitalized children with ARTIs, HAdVs were detected in 2464 cases (7.74%). Annual positivity rates were 4.87% in 2021, 7.21% in 2022, and 4.39% in 2023, and sharply increased to 11.58% in 2024. No significant sex-based difference in infection rates was observed. Distinctly seasonal and temporal patterns were noted, with a pronounced summer peak in 2024 and increased circulation throughout the year. A notable shift in dominant genotypes was observed, with HAdV-C initially prevailing, followed by a surge in HAdV-B between late 2023 and mid-2024. Children aged 1–7 years exhibited the highest positivity rates, indicating age-related susceptibility. Furthermore, co-infections were common and became increasingly predominant after the implementation of tNGS diagnostics, accounting for over 85% of HAdV-positive cases by 2023–2024. These findings suggest a post-pandemic resurgence of HAdV activity, shaped by altered population immunity, resumed social contact, and improved diagnostic sensitivity. Continuous molecular and epidemiological surveillance is essential to guide targeted interventions and inform pediatric respiratory infection management strategies.

Respiratory syncytial virus (RSV) resurged in many regions after the relaxation of stringent non-pharmaceutical interventions (NPIs) implemented during the COVID-19 pandemic. Here, we characterized the epidemiological patterns and molecular evolution of RSV among pediatric inpatients with acute respiratory tract infections (ARTIs) on tropical Hainan Island, China. We retrospectively analyzed 32,329 children (≤18 years) hospitalized at Hainan Women and Children’s Medical Center from January 2021 to December 2024. RSV positivity was determined using targeted next-generation sequencing. In total, 4483/32,329 (13.86%) patients were RSV-positive, with a high positivity in 2021 (20.27%, 957/4721), marked suppression in 2022 (2.03%, 106/5227) during intensive NPIs, and a rebound in 2023–2024 (15.31%, 1490/9732; 15.26%, 1930/12,649). RSV positivity was higher in boys than girls (14.42% vs. 13.00%). Seasonality shifted from a summer–autumn peak in 2021 to a spring–summer predominance in 2023–2024. Among 56 sequenced RSV-positive specimens (29 RSV-A; 27 RSV-B), all RSV-A strains belonged to genotype ON1 (lineages A.D.3 and A.D.5.2), and all RSV-B strains belonged to genotype BA9 (lineages B.D.4.1.1, B.D.E.1, and B.D.E.2). Subtype dominance transitioned from RSV-A (2021–2023; mainly A.D.3) to RSV-B in 2024 (all B.D.E.1). Lineage-specific amino-acid and predicted N-glycosylation changes were observed, including loss of the N179 site in A.D.5.2 and acquisition of N258 in B.D.E.1. These findings indicate that RSV circulation on tropical Hainan was strongly suppressed during intensive NPIs and re-established after policy relaxation, accompanied by earlier seasonal activity and clear lineage replacement, underscoring the need for sustained genomic surveillance to inform locally tailored clinical preparedness and immunization strategies.

Hypervirulent Klebsiella pneumoniae (hvKP) causes invasive and metastatic infections and is increasingly acquiring carbapenem resistance. However, its laboratory identification remains challenging because hypermucoviscosity is an imperfect surrogate for hypervirulence, and no universally accepted diagnostic definition exists. This narrative review critically examines the diagnostic relevance of major virulence determinants, including iucA, iroB, peg-344, rmpA, and rmpA2, in relation to the epidemiologically active lineages that carry them, and compares phenotypic assays, targeted molecular detection, whole-genome sequencing, and emerging analytical technologies, reporting performance estimates together with their evidence base. Particular attention is given to the convergence of hypervirulence and antimicrobial resistance, the frequent discordance between genotype, phenotype and clinical outcome, and the host-dependent variability of clinical expression. We propose a tiered laboratory framework that begins with isolation and identification of K. pneumoniae and that integrates a dedicated antimicrobial-resistance tier with targeted virulence-marker detection and genome-based characterization according to clinical need and laboratory capacity; isolates positive for both resistance and hypervirulence determinants are prioritized for confirmatory genomic characterization. Requirements for analytical validation, quality control, cost and feasibility across laboratory tiers, and the infection prevention and control response triggered by a positive result are also addressed. Standardized diagnostic criteria, externally validated assays, integrated reporting that incorporates host factors, and coordinated genomic surveillance are essential to improving the recognition and management of hvKP and its carbapenem-resistant variants.

Respiratory syncytial virus (RSV) resurged in many regions after the relaxation of stringent non-pharmaceutical interventions (NPIs) implemented during the COVID-19 pandemic. Here, we characterized the epidemiological patterns and molecular evolution of RSV among pediatric inpatients with acute respiratory tract infections (ARTIs) on tropical Hainan Island, China. We retrospectively analyzed 32,329 children (≤18 years) hospitalized at Hainan Women and Children’s Medical Center from January 2021 to December 2024. RSV positivity was determined using targeted next-generation sequencing. In total, 4483/32,329 (13.86%) patients were RSV-positive, with a high positivity in 2021 (20.27%, 957/4721), marked suppression in 2022 (2.03%, 106/5227) during intensive NPIs, and a rebound in 2023–2024 (15.31%, 1490/9732; 15.26%, 1930/12,649). RSV positivity was higher in boys than girls (14.42% vs. 13.00%). Seasonality shifted from a summer–autumn peak in 2021 to a spring–summer predominance in 2023–2024. Among 56 sequenced RSV-positive specimens (29 RSV-A; 27 RSV-B), all RSV-A strains belonged to genotype ON1 (lineages A.D.3 and A.D.5.2), and all RSV-B strains belonged to genotype BA9 (lineages B.D.4.1.1, B.D.E.1, and B.D.E.2). Subtype dominance transitioned from RSV-A (2021–2023; mainly A.D.3) to RSV-B in 2024 (all B.D.E.1). Lineage-specific amino-acid and predicted N-glycosylation changes were observed, including loss of the N179 site in A.D.5.2 and acquisition of N258 in B.D.E.1. These findings indicate that RSV circulation on tropical Hainan was strongly suppressed during intensive NPIs and re-established after policy relaxation, accompanied by earlier seasonal activity and clear lineage replacement, underscoring the need for sustained genomic surveillance to inform locally tailored clinical preparedness and immunization strategies.