In China, waterborne transmission is a relatively rare route for norovirus outbreaks; however, once it occurs, the outbreaks tend to be large in scale, prolonged in duration, and difficult to control. This systematic review characterizes the epidemiological features of such outbreaks in China. We searched the WANFANG, CNKI, PubMed, and Web of Science databases for literature on waterborne norovirus outbreaks published up to November 2023. From 2000 to 2022, a total of 112 outbreaks were reported in China among the 97 articles included. These outbreaks involved approximately 19,796 cases and 565,485 exposures, median of 98 cases per outbreak, with a median attack rate of 6.09 %. Most outbreaks occurred in southern regions, particularly in coastal provinces, with schools (59, 52.68 %) and towns or villages (25, 22.52 %) being the most common settings. The highest number of outbreaks was reported in February and the lowest in July, with an average of 8.25 outbreaks per month. Higher attack rates were associated with outbreaks occurring in winter, in primary schools, and in southern regions of the Qinling-Huaihe line. Contamination of barreled water and self-provided wells was the primary risk factor for waterborne norovirus outbreaks. Although waterborne transmission is a relatively rare route for norovirus outbreaks in China, it can cause large-scale outbreaks in a short period. Consequently, it is still necessary to enhance protection of water sources, rigorous water quality monitoring, and public health education on water sanitation.

Background: Human adenovirus (HAdV) is associated with severe pneumonia and death in children, but its global burden remains unknown. We estimated the global burden of HAdV-associated acute lower respiratory infection (ALRI) among children ≤ 14 years. Methods: We searched six databases from inception to October 31, 2025 for studies reporting laboratory-confirmed HAdV infection during at least 12 consecutive months of surveillance. Random-effects meta-analyses generated epidemiological parameters, including HAdV-associated ARI positivity, HAdV positivity among fatal ARI cases, which were combined with Global Burden of Disease 2023 ALRI estimates and UN population data. We used a pathogen-associated model to estimate HAdV-associated ALRI incidence and mortality rate. The protocol was registered with PROSPERO (CRD420261293361). Findings: We included 149 studies. In 2023, there were an estimated 5·27 (95% UI 4·39 –6·33) million HAdV-associated ALRI episodes and 73 200 (95% UI 44 300 – 117 900) deaths among children ≤14 years, corresponding to rates of 260 and 3·6 per 100 000 children, respectively. Infants < 1 year had the highest incidence rate (511 per 100 000), and 55 200 deaths occurred in children under 5 years. Incidence ranged from 81 per 100 000 in high-income countries to 357 per 100 000 in lower-middle-income countries. Interpretation: HAdV-associated ALRI represents a substantial global burden, particularly among children under 5 years. Standardized surveillance and stronger evidence on severe and fatal outcomes are needed to refine estimates and inform prevention, vaccine research, and resource allocation.

Cases of scarlet fever have increased since 2011 across China. However, genomic epidemiological knowledge of Streptococcus pyogenes, the causative agent, is limited. Here we present a longitudinal analysis of S. pyogenes isolates (n = 1,029) across emm1 and emm12 genotypes collected from eight provinces across China between 1993 and 2024. Genomic data integrated with national scarlet fever incidence data confirmed emm12 and emm1 as dominant genotypes underlying five incidence peaks and disease resurgence in 2024. Phylogenetic analysis showed independent evolution of these genotypes in China compared to global epidemic lineages. Four emm12 clades were present in China before 2011 but were replaced by a single clade, Clade II, by 2020. A dominant emm1 clade, M1china, distinct from global lineages and the M1UK lineage, represents >98% of emm1 cases in China. Sub-clade expansion coincides with carriage of integrative conjugative elements containing macrolide and tetracycline resistance genes and virulence gene-encoding prophage. Ongoing maintenance of these elements in emm1 and emm12 populations likely underlies the resurgence of scarlet fever in China.

Understanding the heterogeneity of population-level viral fitness dynamics, which reflect the interplay between intrinsic viral properties and population immunity, is critical for pandemic preparedness. However, how these dynamics vary across diverse immune backgrounds and mutational landscapes remain poorly characterized. We present Geno-GNN, a graph representation learning approach for retrospectively characterizing the viral fitness dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Geno-GNN accurately predicts angiotensin-converting enzyme 2 (ACE2) binding affinity and immune escape potential across multiple external datasets. Using Geno-GNN, we identified temporal patterns in SARS-CoV-2 fitness and detected varying rates of fitness change associated with distinct immune backgrounds. Virtual mutation scanning revealed two fitness trajectories: broad immune evasion at the cost of ACE2 affinity and ACE2 affinity maintenance at or above the Wuhan-Hu-1 level along with moderate immune escape. Notably, real-world SARS-CoV-2 variants predominantly followed the latter trajectory, sustaining ACE2 affinity via fixed mutations. These findings underscore the heterogeneous, immune-contextualized nature of viral fitness dynamics and the complex evolutionary pathways of SARS-CoV-2.

BACKGROUND:Data on influenza vaccine effectiveness (VE) against hospitalized severe acute respiratory infection (SARI), particularly in Asia, remain limited for the 2025/26 Northern Hemisphere influenza season. This study aimed to evaluate real-world VE against A(H3N2)-associated SARI hospitalization and provide timely, locally relevant evidence to inform seasonal influenza vaccination policy. METHODS:A test-negative design was used to estimate VE against influenza A(H3N2)-associated SARI hospitalization in Beijing, China, from 10 November 2025 to 18 January 2026. VE was estimated by comparing the odds of influenza vaccination between case-patients (those who tested positive for A(H3N2)) with controls (those who tested negative for influenza). RESULTS:Among 1883 enrolled SARI inpatients, 220 (11.7%) tested positive for influenza A(H3N2). Overall vaccination coverage was 11.4%, with the highest coverage observed among children aged 5-17 years (29.6%). Influenza positivity was higher among rural residents, patients with pneumonia or hypoxemia, and those with symptom onset in November. The adjusted overall VE was 7.5% (95% CI: -45.8% to 43.3%). Moderate VE was observed among children aged 5-17 years (45.4%, 95% CI: -33.6% to 79.5%), although the confidence interval included zero and the estimate was not statistically significant. Negative VE estimates were observed among younger children and older adults. Among patients with underlying respiratory conditions, VE was 75.4% (95% CI: -27.4% to 98.7%), although this estimate was also not statistically significant. CONCLUSIONS:During the 2025/26 influenza season in Beijing, VE against A(H3N2)-associated SARI hospitalization was suboptimal. Moderate protection was observed among children aged 5-17 years, the group with the highest vaccination coverage, but the estimate was not statistically significant. The low overall VE may be attributable to antigenic mismatch between vaccine and circulating strains, as well as low population-level vaccination coverage. These findings highlight the need to improve vaccine formulations and increase vaccination coverage, particularly among adults and older populations.

Background:Nirsevimab was first deployed in Beijing through a pilot voluntary, self-pay scheme during the 2024-2025 epidemic season, following its approval in China in December 2023. We aimed to evaluate the real-world effectiveness of nirsevimab against RSV-associated lower respiratory tract infection (LRTI) hospitalisation in Beijing, China. Methods:We conducted a population-based retrospective cohort study using linked, individual-level data from the Beijing Immunisation Information System and Hospitalisation Information System. The study population comprised all infants born between April 1, 2024, and March 31, 2025, in 24 designated pilot maternity hospitals. The primary endpoint was RSV-associated LRTI hospitalisation. City-wide virological surveillance was used to define the population-level exposure risk period. Nirsevimab effectiveness was estimated using Bayesian Poisson regression in a propensity score-matched cohort, with three additional models (Firth penalized Poisson, Bayesian Cox, and Firth penalized Cox) as sensitivity analyses. Findings:Among 44,791 eligible infants, 1166 (2.6%) received nirsevimab. In the propensity score-matched cohort (1129 infants per group), the incidence rates of RSV-associated LRTI hospitalisation were 18.8 vs. 2.3 per 1000 person-years in non-recipients and recipients, respectively. Bayesian Poisson regression demonstrated 83.3% effectiveness (95% CrI: 33.3-97.5%; posterior probability: 0.995). Sensitivity analyses yielded consistent estimates (82.8-84.5%). Analyses in the full cohort produced directionally consistent estimates. Interpretation:This first evidence of nirsevimab's effectiveness in China validates its value in a novel geographical and implementation context, supporting its inclusion as a recommended preventive option. Real-time virological surveillance is essential to optimise immunisation timing amid evolving RSV epidemiology. Funding:Capital's Funds for Health Improvement and Research (2026-1G-3012); Beijing Research Center for Respiratory Infectious Diseases (BJRID2024-002); Beijing Municipal Health Commission's Funds for the High-qualified Public Health Professionals Development Project (Discipline Core-03-36); Capital's Funds for Health Improvement and Research (2024-2-30117).

BACKGROUND:Hand, foot, and mouth disease (HFMD), particularly EV-A71, has caused large-scale epidemics in the Asia-Pacific region, with China alone reporting over 2 million annual cases and causing a substantial morbidity and mortality. While EV-A71 vaccination was introduced in 2016 and COVID-19 non-pharmaceutical interventions (NPIs) were implemented from 2020-2022, comprehensive evidence on their independent and combined effects on HFMD epidemiology remains scarce. We aimed to quantify the impact of vaccination, NPIs, and post-pandemic policy relaxation on HFMD incidence and pathogen distribution. METHODS:We conducted an interrupted time series segmented regression analysis using a 14-year surveillance dataset (January 2011-December 2024) from Beijing's National Notifiable Disease Reporting System and citywide pathogen surveillance network. The study population included all HFMD cases reported in Beijing. We defined four intervention periods: baseline (pre-vaccination), vaccination introduction (August 2016), stringent NPIs (January 2020), and reopening (January 2023). Primary outcomes were HFMD incidence rates and incidence rate ratios (IRRs). We estimated prevented cases under counterfactual scenarios. RESULTS:Among 324,623 reported HFMD cases across the 14-year study period, interrupted time series regression demonstrated that vaccination was associated with a 33% reduction in incidence (IRR 0.67, 95% CI: 0.49-0.91); cumulatively over 8 years (2016-2024), this was estimated to have prevented 23.8% of cases that would have occurred without vaccination. Stringent NPIs were associated with an 84% reduction (IRR = 0.16, 95% CI: 0.06-0.41); cumulatively, during the intervention period (2020-2022), NPIs were estimated to have prevented 82.6% of cases. Following policy relaxation, incidence rebounded 2.53-fold (95% CI: 0.64-9.92), although this increase did not reach statistical significance. In absolute terms, monthly mean case counts declined from 3001 (baseline) to 1886 following vaccination introduction (37.2% decrease), and further to 299 during stringent NPIs (90.0% decrease from baseline), before surging to 1503 post-reopening, a fivefold increase from the NPI period. Pathogen surveillance revealed EV-A71 prevalence declined from 30.5% (baseline) to 4.5% (vaccination period), while coxsackievirus A6 emerged as the dominant serotype, from 9.5% (baseline period) to 56.2% (vaccination period). CONCLUSIONS:EV-A71 vaccination and NPIs were each associated with reduced HFMD transmission, but policy relaxation was followed by a substantial resurgence. The observed serotype replacement with non-vaccine-type enteroviruses highlight critical gaps in current prevention strategies. Sustaining HFMD control requires optimizing vaccine design, developing multivalent vaccines, maintaining high coverage, and integrating targeted NPIs during high-transmission seasons.

Noroviruses are a major cause of acute gastroenteritis worldwide. In Beijing, norovirus GII.17 outbreaks, which dominated in 2014-2015 (66.7%), surged again from 1.3%-12.2% (2015-2024) to 81.7% (2024-2025), with reported outbreaks during July 2024-February 2025 dramatically exceeding the prior year (301 vs. 103). From 2014 to 2025, 249 GII.17 outbreaks were identified, comprising 107 Kawasaki308 (1525 cases) and 142 Romania-2021 (1840 cases) based on phylogenetic analysis. The proportion of outbreak settings differed for Romania-2021 and Kawasaki308: kindergartens (35.2% vs. 37.4%), primary schools (46.5% vs. 29.0%), middle schools (5.6% vs. 12.1%) and others (12.7% vs. 21.5%). Romania-2021 cases were younger and had more vomiting than Kawasaki308 cases. Phylogenetic analysis revealed that novel GII.17 strains dominated in Beijing in 2024-2025 clustered with contemporaneous global strains, forming a distinct subcluster (New_2023-2025) within New (Romania-2021 like) cluster. This subcluster exhibited unique amino acid substitutions in VP1, VP2 and non-structure proteins compared to other clusters and New subclusters. Our findings confirm the dominance of Romania-2021 like strains during 2024-2025 in Beijing. Differences in symptom profiles and affected age groups between Kawasaki308 and Romania-2021, and unique amino acid substitutions may help explain the rapid predominance of the emerging cluster.

Norovirus is the leading cause of acute gastroenteritis outbreaks worldwide. A total of 1859 norovirus outbreaks were reported from 2016 to 2022 in Beijing, China. GII.2[P16] was the predominant genotype during 2016-2021, and GII.3[P12] during 2021-2022. In the early stage of the COVID-19 epidemic (January to June of 2020), strict prevention and control measures were implemented, and only eight norovirus outbreaks were reported. Most norovirus outbreaks occurred in schools (95.6%, 1778). As the level of schooling rises, the scale of norovirus outbreaks also increases (median case numbers: 8 for kindergarten, 10 for primary school, 11 for secondary school, and 14 for college; p trend < 0.001), while the attack rate decreases (median attack rates were correspondingly 25.8%, 17.5%, 10.0%, and 8.8%; p trend < 0.001). Compared to outbreaks caused by person-to-person transmission, foodborne and waterborne outbreaks are larger in scale. Delayed outbreak response is also a risk factor for larger-scale outbreaks. Norovirus outbreaks have emerged as a significant concern for public health in Beijing. Persistent genotyping efforts are essential to facilitate early warning. Outbreaks in different locations or through different transmission routes require specific prevention and control measures.

During the early 2025/26 influenza season, influenza A(H3N2) subclade K rapidly predominated in Beijing, China. Using a test-negative design, we estimated influenza vaccine effectiveness (VE) among influenza-like illness outpatients tested between weeks 40/2025 and 04/2026. Among 10,484 participants, sequencing of 316 randomly selected A(H3N2)-positive samples showed 84.8% were subclade K, and antigenic analysis of 65 viruses indicated antigenic divergence. Despite this, adjusted VE against laboratory-confirmed influenza was 23.5% (95% confidence interval: 11.7–33.7), indicating modest protection during this subclade K-dominated season.

Objectives:To analyze the epidemiological characteristics and estimate the incidence of infectious diarrhea in Beijing, China, 2015-2019. Methods:From January 2015 to December 2019, stool specimens and epidemiological data of diarrhea cases were collected from sentinel hospitals across all districts. Viral pathogens were detected by real time PCR or RT-PCR, including rotavirus, norovirus, astrovirus, adenovirus and sapovirus. Bacterial pathogens were detected using culture, biochemical and serological assays, including Vibrio cholerae, Shigella, Salmonella typhi and Salmonella paratyphi, diarrheagenic Escherichia coli (DEC), non-typhoidal Salmonella (NTS), Vibrio parahaemolyticus, Campylobacter and other bacteria. Descriptive statistics and a Monte Carlo multiplier model were applied for analysis and incidence estimation. Results:A total of 27,804 outpatients were included from 2015 to 2019. Among cases tested for viral pathogens (N = 9,351), norovirus (1,572/9,351, 16.81%) was the most prevalent, followed by rotavirus (907/9,351, 9.70%). Among those tested for bacterial pathogens (N = 20,741), diarrheagenic Escherichia coli (DEC) (1,941/20,741, 9.36%) was predominant, followed by non-typhoidal Salmonella (NTS) (4.55%) and Vibrio parahaemolyticus (4.17%). Notably, enteroaggregative E. coli (35.65%) was the predominant type of DEC identified in this study. The detection rates of viral pathogens were higher in winter and spring. Rotavirus was mainly identified in cases under 5 years of age, while norovirus was more common in cases aged 18-40 years old. Bacterial pathogens were mainly identified in cases aged 18-40 years old in summer. Estimated by the model, the average annual number of infectious diarrhea cases in Beijing from 2015 to 2019 was approximately 68,054 (95%CI: 49,917-104,149). While the model result indicates the presence of significant hidden burden, but are constrained by inherent limitations in the modeling approach and monitoring design. Conclusion:Diarrhea remains a serious public health problem in Beijing, China. Norovirus, DEC, and rotavirus were the predominant pathogens among diarrhea outpatients in Beijing. Continuous surveillance is necessary for guiding prevention and control strategies.

Inactivated vaccines are critical to COVID-19 immunization, yet the cellular and molecular mechanisms driving pediatric responses warrant detailed characterization. We use single-cell transcriptomics to delineate the immune landscape of peripheral blood mononuclear cells in children vaccinated with CoronaVac. We uncovered a two-phase program: the primary dose establishes a memory foundation via expansion of survival-programmed memory B cells and a shift in CD8+ T cells toward stress adaptation. The booster triggers an effector response marked by plasma cell differentiation, class-switching, and a pan-B-cell type I interferon signature. Concurrently, vaccination reprograms monocytes into a pro-inflammatory, antigen-presenting state enriched for interferon-stimulated genes. This activation is counterbalanced by expanded myeloid-derived suppressor cells and FOXP3+ regulatory T cells, which employ PGE2 signaling to restrain excessive cytotoxicity and orchestrate helper T-cell differentiation. Together, our atlas demonstrates that pediatric immunity to inactivated vaccines is tightly orchestrated, balancing antiviral programs with regulatory mechanisms to ensure safe protection.

OBJECTIVES:This study aimed to investigate the prevalence of diarrhoeagenic Escherichia coli (DEC) among outpatients in Beijing, and to analyse the antimicrobial susceptibility profiles and antimicrobial resistance gene characteristics of the isolated strains. METHODS:From 2021 to 2024, DEC strains were collected from outpatient specimens. After isolation and identification, the minimum inhibitory concentration (MIC) method was used to assess their susceptibility to 16 antibiotics. Whole-genome sequencing was conducted for further analysis. RESULTS:Among the 1209 DEC strains, the highest resistance rates were observed for ampicillin (63.28%) and tetracycline (45.57%). In contrast, significantly lower rates were found for tigecycline (0.41%), amikacin (0.66%), meropenem (3.97%), ertapenem (6.70%), ceftazidime (7.20%), and ciprofloxacin (9.26%). The 0-5 age group demonstrated higher resistance rates to most antibiotics compared with other age groups. Multi-locus sequence typing revealed significant genetic diversity among all strains, with the predominant sequence types identified as ST10 (5.96%), ST1491 (5.21%), ST4 (4.22%), and ST48 (3.47%). Among 111 fluoroquinolone-resistant strains, chromosomal mutations in gyrA and parC genes were predominant (56.76%). Among 612 cephalosporin-resistant isolates, the blaCTX-M gene was the most prevalent resistance gene (30.72%). CONCLUSIONS:DEC infections and the spread of resistance genes pose a significant health threat, especially in children. Consequently, there is an urgent need to enhance the surveillance and research of resistance genes and to promote the rational use of antibiotics.

Influenza A virus (IAV) infection has a wide clinical spectrum, from mild illness to life-threatening pneumonia, yet the underlying immune determinants of disease remain poorly defined. Here, we generated a large-scale single-cell transcriptomic atlas from peripheral blood, profiling more than 612,010 cells from 97 individuals, including healthy controls, and patients with mild, severe, or convalescent IAV infection. Our findings uncovered a core immune dichotomy that determines clinical severity: a protective, monocyte-centric antiviral state in mild disease versus a pathological, neutrophil- and myeloid-derived suppressor cell (MDSC)-driven hyperinflammatory state in severe infection. Severe disease was marked by a peripheral hyperinflammatory state, driven by specific monocyte and neutrophil subsets via the S100A8/9/12-TLR4/RAGE signaling axis, and was coupled with the expansion of granulocytic MDSCs that likely contribute to T cell paralysis. In contrast, mild disease was associated with a protective, monocyte-centric response characterized by robust antiviral interferon signaling and enhanced antigen presentation. This functional divergence extends to the adaptive immune system, where mild disease was associated with CD8+ T cells displaying a balance of high cytotoxicity and regulated exhaustion. In severe illness, however, T cells become profoundly dysfunctional, exhibiting signatures of metabolic stress and apoptosis alongside the emergence of pathogenic, pro-inflammatory regulatory T cells. Together, our atlas provides a high-resolution immunological blueprint of human IAV infection, delineates the cellular states and pathways that govern clinical trajectories and offers a critical resource for developing host-directed therapies.

Other Infectious Diarrheal Diseases (OIDD), caused by pathogens excluding Vibrio cholerae, Shigella, Salmonella typhi, and Salmonella paratyphi, remain a significant public health concern in China. Beijing, a megacity with high population density, extensive mobility, and a temperate monsoon climate, is a prototypical example of temperate monsoon megacities globally. Long-term OIDD patterns, spatiotemporal distribution, and future trends in such dense urban settings are poorly understood, and insights from Beijing can provide valuable guidance for similar cities worldwide. We retrieved case data on OIDD reported in Beijing during 2004-2024 from the Chinese Disease Prevention and Control Information System. Descriptive epidemiology, spatial autocorrelation analysis, hotspot analysis, and the Seasonal Autoregressive Integrated Moving Average (SARIMA) model were employed to investigate the temporal, demographic and regional distribution patterns, identify high-risk regions, and forecast the incidence of OIDD for 2025. A total of 756,933 OIDD cases were reported over the 21-year period. Incidence exhibited an overall downward trend from 2006 to 2022, followed by a rebound from 2023 to 2024. Seasonal peaks occurred in summer (July-August) and winter (December-January), with a notable shift of the summer peak to April-May in 2023. The under-1 year age group showed the highest average annual incidence rate (3502.75 per 100,000), and males were more affected than females (male-to-female ratio 1.19:1). Spatial analysis revealed significant clustering (Moran’s I = 0.18-0.44, P < 0.01), with high-high clusters shifting from central urban districts to suburban areas over time, while persistent low-low clusters were observed in remote districts. The SARIMA (1,1,1) (1,1,1) ₁₂ model accurately predicted monthly cases in 2024 (MAPE = 17.46

OBJECTIVES:Schools are high-risk settings for influenza transmission. During the 2025-26 Northern Hemisphere season, influenza A(H3N2) subclade K (J.2.4.1) rapidly emerged and became predominant, but vaccine effectiveness (VE) in school-associated outbreaks remains unclear. METHODS:We conducted a field investigation of 93 school-associated febrile outbreaks in Beijing, China, from September to December 2025. Cases were febrile students with laboratory-confirmed influenza, and afebrile classmates served as controls. VE against laboratory-confirmed symptomatic infection was estimated using mixed-effects logistic regression, adjusting for age, sex, school type, and outbreak-level clustering. RESULTS:A total of 3797 students were included, of whom 788 were laboratory-confirmed febrile cases and 3009 were afebrile classmates. Primary schools accounted for 74.2% of outbreaks. Overall vaccination rate was 54.6%, with 50.6% among cases and 56.1% among controls. Unadjusted VE was 19.6% (95% CI: 5.9-31.3). After adjustment, VE against laboratory-confirmed influenza was 30.0% (95% CI: 17.3-40.7). Sensitivity analyses yielded consistent results. CONCLUSION:Influenza vaccination provided modest protection against symptomatic A(H3N2) infection in school-aged children, even under conditions of high-intensity exposure and antigenic drift. These findings underscore the value of vaccination in outbreak-prone school settings and highlight the importance of ongoing vaccine strain optimization and outbreak-based VE surveillance.

BACKGROUND:Interactions between SARS-CoV-2, influenza virus, and respiratory syncytial virus (RSV) at the population level remain poorly understood. This study aimed to quantify potential interactions among these viruses and assess their influence on transmission dynamics. METHODS:We analyzed weekly surveillance data on SARS-CoV-2, influenza A and B viruses (IAV and IBV), and RSV from seven regions from October 2021 to May 2024. Distributed lag nonlinear models within a spatiotemporal Bayesian hierarchical framework were used to assess the exposure-lag-response associations among virus pairs. Additionally, we developed a two-pathogen, meta-population mechanistic transmission model to capture the co-epidemic dynamics of IAV and SARS-CoV-2, and to quantify the strength and duration of their bidirectional interactions. RESULTS:Among all virus pairs examined, a statistically significant association is identified only between IAV positivity and subsequent SARS-CoV-2 risk. When IAV positive rate percentile is between the 52nd and 88th percentiles, the relative risk (RR) of SARS-CoV-2 infection is significantly reduced. The lowest RR for SARS-CoV-2 (0.58, 95% CrI: 0.40-0.85) occurs at a 5-week lag when IAV positivity reaches the 70th percentile. The fitted mechanistic model using incidence data in Beijing shows that IAV infection substantially reduces infection to SARS-CoV-2 by 94.24% (95% CrI: 88.50%-99.24%), with the protective effect lasting 38.24 days (95% CrI: 35.50-41.29 days). Conversely, SARS-CoV-2 infection is associated with a slight increase in infection to IAV. CONCLUSIONS:Our findings indicate that IAV circulation may transiently reduce population-level infection to SARS-CoV-2, potential through ecological or immunological mechanisms.

Toxigenic Vibrio cholerae (V. cholerae) was first sensitively and rapidly detected in hospital wastewater in Beijing, China, on 12 June 2025. Viable V. cholerae was successfully isolated from the wastewater sample and identified as the O1 Ogawa serotype. Whole-genome sequencing and comparative genomic analysis revealed that the isolate was closely related to locally circulating strains but clearly distinct from the seventh pandemic lineage, suggesting its link to indigenous transmission chains. In addition, we immediately initiated a comprehensive and multi-source traceback investigation upon detection of this positive signal, integrating clinical, environmental, and epidemiological data. This case highlights the early-warning and situational-awareness value of wastewater surveillance in detecting emerging pathogens and emphasizes its indispensable role in infectious disease prevention and control systems, providing a scientific basis for timely public health decision-making.