The Lancet Infectious Diseases

Background: Mucosal immunity is critical for preventing poliovirus transmission. Despite evidence that infant immunisation protects against poliovirus infection into adulthood, the duration of vaccine-induced intestinal antibody responses remains poorly characterised. Methods: We evaluated poliovirus type-specific neutralising activity and immunoglobulin levels in stool and serum from children in Tanzania who completed routine poliovirus vaccine series (bivalent oral polio vaccine at birth, 6, 10, and 14-weeks, and inactivated polio vaccine at 14-weeks). The study included a longitudinal cohort with four visits over 6 months and a cross-sectional sample of children recruited 1 to 108-months after vaccine series completion. Potential modification by nutritional factors, gastrointestinal infections, and environmental enteropathy was explored. Findings: Among 103 longitudinal and 246 cross-sectional participants enrolled, 33% and 18% had positive poliovirus type-1 (PV1) stool neutralisation, and 66% and 56% had positive poliovirus type-3 (PV3) neutralisation 1 month after vaccination. All were seropositive for PV1 and PV3 across timepoints. Infants followed longitudinally who were stool neutralisation-positive at enrolment had no boost in neutralisation after vaccination, while those stool neutralisation-negative at enrolment experienced a weak boost at 1 month. Stool neutralisation half-life among longitudinal cohort infants was 3.4 months [95% CI 2.6-5.0] for PV1 and 1.7 months [1.4-2.3] for PV3. Moderate evidence suggested concurrent viral intestinal infections were associated with lower neutralisation responses (PV1 p=0.153; PV3 p=0.052). Interpretation: Intestinal antibody responses to poliovirus vaccination were short-lived. The impact of waning intestinal antibodies on transmission risk remains unclear and research is needed to identify vaccination strategies that induce durable mucosal immunity.

Background: The World Health Organization has expanded its recommendations for prophylactic Ebola vaccination for at-risk populations. Durable vaccine-induced immunity is important for sustaining outbreak preparedness in regions with recurrent Ebola virus disease (EVD). We assessed five-year persistence of vaccine-induced immune responses in adults and children from the PREVAC trial. Methods: Two large randomised phase 2 trials (NCT02876328), in adults and children aged [≥]1 year, were conducted in four west African countries. Participants were randomly assigned to placebo or to one of three Ebola vaccine strategies: Ad26.ZEBOV followed by MVA-BN-Filo at 56 days; rVSV{Delta}G-ZEBOV-GP followed by placebo; or rVSV{Delta}G-ZEBOV-GP followed by a homologous booster dose at 56 days. After 12 months of follow-up, the primary results were published, participants unblinded to their vaccine assignment, and follow-up continued for 60 months. After Month 24, placebo group recipients were offered active vaccination. Anti Ebola virus glycoprotein Immunoglobulin G (IgG) concentrations were measured for 5 years. Findings: 1401 adults and 1401 children were initially randomized, and 1315 (93.9%) adults and 1322 (94.4%) children attended at least one long-term visit. Retention was high, with 95% followed beyond 1 year and 83% completion at 5-year follow-up. For the three vaccine strategies, antibody geometric mean concentrations (GMC) declined modestly between Months 12 and 24, followed by a stable plateau from Months 24 to 60. At Month 60, antibody GMC were higher in the rVSV-based groups (1099 and 1216 EU/ml for adults; 1982 and 2347 EU/ml for children) than in the Ad26.ZEBOV, MVA-BN-Filo group (252 adults and 645 EU/ml children). Antibody persistence at Month 60 was heterogeneous, varying by age, sex, country, and baseline IgG concentration. Interpretation: Licensed Ebola vaccines induced sustained antibody responses in adults and children for up to 5 years. While the protective antibody level is unknown, these data demonstrate long-lasting immune responses from currently employed vaccine strategies.

Filoviruses pose a threat to individuals and the global community as pathogens of pandemic potential. The scientific community faces an ongoing challenge of developing effective vaccines with unpredictable outbreaks concentrated in countries with lower healthcare resources. Given these limitations, it is important to ensure that existing filovirus research is used as efficiently as possible. To enable rapid identification and use of this research, we have developed evidence maps of existing filovirus publications to enable further analysis and synthesis. We systematically identified and categorised existing immunological and clinical publications on Bundibugyo (BDBV), Marburg (MARV), Sudan (SUDV) and Ebola (EBOV) viruses. We captured studies that reported on animal or human immune responses to infection, outcome of infection, or human vaccine safety data. Initial searches of PubMed, Embase and Europe PMC were run between November 2024 and January 2025 and the MARV, SUDV and EBOV searches were updated on 1 August 2025. A BDBV search was conducted on 18 May 2026 in response to the WHO declaration of a Public Health Emergency on 17 May 2026. The initial searches retrieved 208, 1646, 534 and 3963 manuscripts for BDBV, MARV, SUDV and EBOV, respectively. After screening using an a priori exclusion criteria, 49 BDBV, 198 MARV, 149 SUDV and 850 EBOV publications were included on each evidence map. These maps provide a comprehensive, transparent and reproducible structure to categorise existing studies of filovirus vaccination and immunity. They allow rapid identification of the totality of available evidence and the existing experimental tools to support vaccine development for these priority pathogens.

SARS-CoV-2 continues to evolve from the Omicron serotype, with BA.2.86 sublineage JN.1 and descendants such as KP.2 predominating in 2025-26. By early 2026, the JN.1-derived NB.1.8.1 and XFG variants had largely replaced other variants globally, with a more recent emergence of the highly divergent BA.3.2 saltation variant. Elderly individuals continue to be at greatest risk of clinical complications from COVID-19, yet contemporary data on kinetics of immune potency and breadth following multiple vaccinations remain very limited in this group. We studied a cohort of forty-three healthy older adults (median age = 85 years, IQR 75-88, 40% female). Using both pseudotyped virus (PV) and surrogate virus neutralisation (SVNT) based assays, we demonstrate that JN.1 and KP.2 vaccinations six months apart elicit high potency neutralisation across all studied variants except BA.3.2.2, which escaped neutralisation almost completely in all individuals. Waning of neutralising activity in serum was observed to be modest in the [~]6 months between vaccine doses, suggesting sustained immunity following multiple vaccines. While absolute neutralisation titres remained highest against ancestral Wu-1 at all timepoints due to multiple historical exposures and accumulation, the recall responses revealed a shift in immunodominance. After the recent KP.2 vaccine dose, neutralisation against full-length Wu-1 spike was not boosted, whereas all tested JN.1 descendants and BA.3.2.2 showed significant boosts, indicating that immune imprinting against ancestral Wu-1 was partially overcome. Interestingly, RBD-specific neutralising responses experienced a boost following KP.2 vaccination, suggesting that RBD responses remain imprinted but that they constitute a small proportion in the overall Wu-1 neutralising response as immune imprinting is alleviated.

Background Community-wide active case-finding (ACF) is being increasingly implemented as a tuberculosis (TB) elimination intervention. However, conventional site selection strategies may result in low yields from screening. We evaluated whether an artificial intelligence (AI) software guided targeting strategy could improve detection of TB during screening activities (called camps) relative to routine approaches to site selection in the programmatic setting in Pakistan. Methods We conducted a stepped-wedge cluster-randomised trial embedded within Global Fund supported ACF activities implemented by Pakistan s National TB Program and private sector partners. Thirty mobile X-ray van teams operating in 68 districts were randomly assigned to transition from routine site selection approaches (based on field-staff experience and historical data) to an AI-guided targeting strategy, using the software MATCH-AI. We assessed the effect of the intervention on the primary outcome, Camp Positivity Yield, defined as the number of individuals diagnosed with bacteriologically confirmed TB per camp, using generalised linear mixed models. The primary analysis was by intention to treat. Camps conducted within a 5-km radius of the AI selected locations were included in a validated per-protocol analysis. We conducted several district-level subgroup analyses. This trial is registered, number NCT06017843. Findings Between August 2023 and September 2024, 3,936 screening camps were conducted (2,046 control, 1,890 intervention), screening 269,254 individuals. In the intention-to-treat analysis, Camp Positivity Yield was 7% higher in the intervention group relative to the control group, however this difference was not statistically significant (adjusted risk ratio [RR] 1.07, 95% CI: 0.94 -1.22). In the validated per-protocol analysis, Camp Positivity Yield was 32% higher in the intervention group relative to the control group (adjusted RR 1.32, 95% CI: 1.12-1.54). Yields were highest in districts that had moderate baseline yields of 0.5-1% per population screened prior to the trial (adjusted RR: 1.57, 95% CI: 1.13 - 2.18) and in rural districts (adjusted RR 1.43, 95% CI: 1.23 -1.65). Interpretation The use of an AI-guided targeting strategy significantly increased detection of bacteriologically confirmed TB during active case-finding in the validated per-protocol analysis, relative to conventional site-selection approaches employed by field-staff. This software may be considered as a supportive tool to improve the efficiency of community-based TB case-finding interventions in other high burden countries.

The emergence of the SARS-CoV-2 Omicron BA.2.86 subvariant, a lineage derived from the BA.2 strain, led to the 2024-2025 COVID-19 vaccine update to include KP.2 or related JN.1-lineage spike antigens. We evaluated the magnitude, breadth, and durability of humoral immune responses following a single KP.2 vaccine dose in a longitudinal cohort of 21 individuals up to six months. KP.2 vaccination increased spike-specific binding and neutralizing antibodies against the ancestral WA1 strain, alongside the BA.5, XBB.1.5, and KP.2 variants. Power law modeling estimated half-lives for WA1- and KP.2-specific IgG responses at 770 and 248 days, respectively. Additionally, the KP.2 dose increased IgG1 and IgG4 subclasses more than IgG2 and IgG3 responses to both spike proteins. Serum depletion experiments using WA1 or KP.2 proteins demonstrated most vaccine-elicited antibodies were cross-reactive. Consequently, KP.2 vaccine-induced antibodies retained broad neutralizing activity against recently circulating Omicron subvariants (BA.2.86, KP.3.1.1, XEC, LP.8.1, LF.7, XFG.3.12, PQ.1, BA.3.2.1, and RE.2). Using a live virus neutralization assay, XFG.3.12 showed the greatest reduction in neutralizing titers relative to KP.2 (4.2-fold). In a small subset, an LP.8.1 vaccine dose increased neutralizing activity against the matched variant while maintaining WA1 and KP.2 cross-reactivity, but only modestly increased antibodies to divergent variants BA.3.2.1 and RE.2. Ultimately, these data indicate the KP.2 mRNA vaccine generates durable, cross-reactive responses against current Omicron subvariants. However, ongoing spike evolution impacts neutralization of emerging lineages, highlighting the need for continued viral monitoring and timely vaccine updates. IMPORTANCESARS-CoV-2 continues to evolve, raising ongoing concerns about how well updated vaccines protect against emerging variants. This study evaluates antibody responses after KP.2 spike mRNA vaccine dose and shows that a single dose induces durable and broadly cross-reactive immunity against both earlier strains and recently circulating Omicron subvariants. Despite this breadth, reduced neutralizing activity against certain emerging variants indicates that ongoing antigenic changes can impact vaccine induced antibody effectiveness. These findings provide insight into how current vaccines perform over time and highlight the need to track viral evolution and update vaccine antigens to maintain broad protection against severe disease, hospitalization, and death.

Background: The ongoing Bundibugyo virus disease (BDBV) outbreak in Central Africa highlights the absence of approved vaccines specifically targeting BDBV. Whether licensed Zaire ebolavirus (EBOV) vaccines induce cross-reactive immunity against BDBV remains largely unknown. Methods: We performed an immunogenicity analysis using serum samples from participants enrolled in the PREVAC randomized clinical trial evaluating licensed Ebola vaccine strategies in West Africa. Samples collected at day 28 (D28) and month 3 (M3) following vaccination with rVSV{Delta}G-ZEBOV-GP or Ad26.ZEBOV/MVA-BN-Filo were assessed using a multiplex Luminex assay against glycoproteins from multiple filoviruses, including EBOV Kikwit, EBOV Mayinga, BDBV, Sudan virus, Reston virus, and Marburg virus. Results: A total of 179 samples were analysed. Detectable cross-reactive antibody responses against BDBV were observed across vaccine groups, timepoints, and age categories. However, BDBV responses remained substantially lower than homologous EBOV responses. In rVSV recipients, median BDBV responses (net MFI) reached 282 (IQR 164-644) at D28 compared with 1788 (832-3311) against the homologous Kikwit antigen. Similar patterns were observed following rVSV booster vaccination and Ad26.ZEBOV/MVA-BN-Filo vaccination. The heterologous Ad26/MVA regimen demonstrated increasing BDBV responses between D28 and M3. Conclusions: Licensed EBOV vaccines induced detectable but quantitatively reduced cross-reactive antibody responses against BDBV. Although no direct assessment of vaccine efficacy against BDBV disease was possible, these findings support the plausibility of partial heterologous immunity following EBOV vaccination. In the absence of approved BDBV-specific vaccines, these data support the urgent evaluation of currently available Ebola vaccines during BDBV outbreaks and reinforce the importance of developing broadly protective pan-filovirus vaccines.

Of the two influenza A virus (IAV) subtypes circulating endemically in humans, A/H3N2 and A/H1N1pdm09, A/H3N2 has historically been the dominant driver of disease burden in older adults. Based on an analysis of publicly available global surveillance data from 2015 to 2025 (>300,000 subtyped, age-stratified infections), we report a substantially increased contribution of A/H1N1pdm09 to influenza morbidity in older adults since approximately 2022. Birth cohort-stratified analyses suggest elevated A/H1N1pdm09 burden among individuals born before 1955-1959, consistent with erosion of pre-existing immunity originally generated by exposure to historical A/H1N1 strains. Pooled estimates across datasets and analytical approaches indicate the increase in A/H1N1pdm09 burden rises with earlier birth year, ranging from 1.22-fold (95% CI 1.08-1.37) for the 1955-1959 birth cohort to 3.10-fold (95% CI 2.58-3.72) for the 1930-1934 cohort. These findings point to a substantial rise in the overall influenza burden among the most vulnerable age groups, with implications for vaccine policy, clinical management, and public health planning.

Background. Despite the decline of the 2022 global outbreak, mpox remains an ongoing public health concern, with persistent transmission and emerging viral clades sustaining resurgence risk. Improving preparedness and response is a priority, yet it remains unclear how best pre-exposure vaccination and community response can effectively limit transmission under realistic conditions and whether behavioral adaptation is critical. Methods. We used a data-driven network model of mpox transmission among men who have sex with men in the Paris region, parameterized with sexual behavioral data and calibrated to surveillance data from the 2022 outbreak. We evaluated counterfactual scenarios by varying vaccination timing, rollout speed, prioritization, and behavioral responses. Results. Here we show that, with respect to the 2022 epidemic in the Paris region, vaccination alone delivered at the observed rollout speed would not have reproduced the observed epidemic decline, even if initiated the day of the first European alert, corresponding to 12 days before the first case was reported in France. Achieving comparable control through vaccination alone would have required more than a fourfold increase in rollout speed. Large-scale and long-term reductions in sexual contacts remain instrumental to limit the epidemic size, although earlier vaccination reduces the proportion of MSM needing to change behavior. In contrast, short-term behavioral measures adopted by the vaccinees, such as sexual abstinence during the 14-day immunity-building period, combined with moderately faster vaccine rollout, (+68% for 50% compliance; +34% for 75% compliance) could achieve comparable epidemic control. Targeting individuals with higher sexual activity further improved intervention efficiency. Conclusions. Under realistic reactive vaccination scenarios, mpox control still requires strong behavioral responses. Combining timely vaccination with short-term behavioral change guidance at vaccine administration offers a feasible path to limit transmission and strengthen outbreak preparedness and response.

Tuberculosis (TB) remains a major global health challenge, particularly in low- and middle-income countries such as Mozambique. To address this burden, promising new preventive TB vaccines targeting adolescents and adults are currently in phase III efficacy trials. This study aimed to assess stakeholders perspectives on priority high-risk groups, the challenges in reaching them, and potential strategies for delivering a TB vaccine. We conducted a qualitative study using semi-structured interviews with members of the National TB Program, the National Immunization Program, and the National Immunization Technical Advisory Group. Data were collected between March and July 2024. Our findings suggest that a TB vaccine program in Mozambique should prioritize individuals with comorbidities, especially those living with HIV or diabetes, and close contacts of TB patients, followed by healthcare workers, miners, and incarcerated populations. Although uptake is expected to vary across groups, relatively high coverage was anticipated among people living with HIV, TB contacts, and older adults, as well as healthcare workers, incarcerated individuals, formal miners, and in-school adolescents. To improve uptake, campaign-based strategies using mobile brigades were considered promising approaches to expand coverage. Stakeholder perspectives highlight the importance of prioritizing high-risk groups and adopting context-specific delivery strategies to support the effective introduction of a TB vaccine in Mozambique. Clinical trial numbernot applicable.

Background: Malaria exposure has been hypothesized to alter immune responses to childhood vaccines, but evidence is inconsistent. We evaluated whether early-life malaria exposure and perennial malaria chemoprevention (PMC) modify antibody responses to the 10-valent pneumococcal conjugate vaccine (PCV-10) among infants in a high malaria transmission setting in eastern Uganda. Methods: This study was nested within the MIC-DroP trial (NCT04978272) whereby 202 infants were selected for inclusion. Serotype-specific IgG concentrations were measured using an in-house multiplex seroassay from samples obtained at 8 and 24 weeks of age. Immunogenicity was quantified as the log10 fold-change in IgG concentration between the 8 and 24-week timepoints, and seroconversion as [&ge;]0.35 g/mL at week 24 (i.e., seropositive). Generalized estimating equation models were used to assess associations of PCV-10 immunogenicity and seroconversion with malaria exposure, malaria chemoprevention and birth outcomes. Results: Among the 195 of 202 infants who completed the three-dose PCV-10 series, neither infant PMC nor malaria exposure from study enrollment to 14 weeks were associated with PCV-10 immunogenicity or seroconversion. In contrast, low birthweight (<2500g) was associated with lower immunogenicity (82% lower antibody fold-change, p=0.003) and reduced odds of seroconversion (OR=0.19, p=0.003); preterm birth (<37 weeks) showed similar associations (79% lower antibody fold-change, p=0.018; OR=0.181, p=0.009). Conclusion: In this malaria-endemic setting, early-life malaria exposure and chemoprevention did not measurably alter PCV-10 antibody responses. However, low birthweight and prematurity were associated with reduced vaccine immunogenicity.

The recent development of new respiratory syncytial virus (RSV) prophylactics for the prevention of severe lower respiratory tract infections in infants and older adults promises in lowering disease burden in these vulnerable populations. However, it remains unclear if periodic breakthrough infections in these populations may drive the emergence of resistant isolates or clades and what factors might contribute to these breakthroughs. In this retrospective cohort study, we performed whole-genome sequencing of RSV isolates from infants and adults during the past two RSV seasons (2023-2025) to assess viral and clinical correlates of nirsevimab breakthrough. RSV infections from nirsevimab breakthrough cases were associated with less severe clinical outcomes in the first, but not second, season after administration. While breakthrough isolates did not share any Fusion glycoprotein mutations in predicted antigenic sites, they largely belonged to only a few circulating clades that were responsible for driving temporally distinct pediatric transmission clusters. To determine if these transmission clusters and breakthrough infections were in part driven by differences in the Fusion proteins of these clades, we compared the relative fusogenicity and neutralization susceptibility of Fusion proteins from contemporary circulating clades. Notably, RSV-A clade A.D.3 exhibited modestly reduced susceptibility to nirsevimab neutralization, though it wasnt associated with any transmission clusters or breakthrough infections. Collectively, these data suggest that clade associations with prophylactic breakthrough are driven by pediatric transmission clusters rather than clade-associated resistance, though continued surveillance will be vital as prophylactic coverage continues to rise.

Pooled testing programs were introduced during the COVID-19 pandemic to expand surveillance capacity while preserving testing resources, but evidence on their epidemiological impact in schools under real-world conditions remains limited. We analyzed data from the pooled testing program implemented in public primary schools of the canton of Basel-Landschaft, Switzerland, during the Fall-Winter 2021 Delta wave. We used an agent-based transmission model informed by pooled and individual testing results, school characteristics, contact networks, and community incidence. The model was fitted to pooled positivity ratios in four clusters of administrative areas with similar epidemic trajectories. We compared pooled testing with alternative protocols in terms of school transmission, testing volume, and student-days lost. During the study period, pooled testing was offered to 21'187 students across 62 public primary schools, with high and stable participation across clusters (mean 71-79%). The fitted model reproduced observed pool positivity trends well. Compared with pooled testing, reactive class closure, reactive screening, and symptomatic testing were associated with higher in-school transmission, with excess ranging from 50% to 87%, 63% to 104%, and 72% to 133% across clusters. Weekly individual screening achieved similar reductions in transmission but required 15-25 times more tests. Relaxing class closure after depooling substantially reduced student-days lost without increasing transmission. Under real-world conditions, pooled testing provided an effective and resource-efficient strategy to reduce SARS-CoV-2 transmission in primary schools. Combining early detection of asymptomatic infections with low testing demands, pooled testing offers a scalable approach to school surveillance and control for pandemic response in educational settings.

Objectives Tuberculosis (TB) in the United States disproportionately affects non-U.S.-born individuals. While testing this population for TB infection is recommended, little is known about individuals' willingness to take treatment for latent TB infection (LTBI). To address this gap, we conducted a pilot preference survey among individuals from countries with high TB incidence. Design Cross-sectional survey supported by language concordant community health workers. Setting Federally qualified health center, serving a primarily Asian immigrant community, in San Francisco. Participants Adults eligible for risk-based LTBI testing based on place of birth seeking primary care. Outcome measures Perspectives on TB disease, risk of reinfection, and willingness to accept treatment if diagnosed with LTBI conditional on different factors, such as side effects, costs, and other treatment burden. Results Among 60 participants, the median age was 48 years (interquartile range 35-63 years), 52% were women, and 100% spoke Chinese. Infecting others (n=35, 58%), risk of death (n=30, 50%), and potential isolation (n=25, 42%) were the most worrisome consequences of TB disease. Reinfection risk, risk of liver damage, cost, TB progression risk, clinic visits, and blood draws were most often considered moderately or very important when deciding whether to take LTBI treatment (n=53 to 57, 88-95%). While most participants (n=56, 93%) were willing to take treatment if diagnosed with LTBI even at a 10-year TB progression risk below 1% and willing to accept a risk of liver damage (n=41, 68%), less than half would accept LTBI treatment if there were any associated cost (n=28, 47%). Finally, many participants had concerns about their reinfection risk after completing LTBI treatment (n=34, 57%). Conclusions Amongst surveyed participants, TB disease and its consequences such as hospitalization, death and infecting others were worrisome, and participants had a high level of willingness to take treatment if diagnosed with LTBI. Future assessments of how people weigh tradeoffs regarding LTBI diagnosis and treatment could inform interventions to increase LTBI treatment acceptance and completion.

Background Artemisinin derivatives are central to first-line treatment of both uncomplicated and severe Plasmodium falciparum malaria. Emerging artemisinin partial resistance in East Africa threatens to spread across the continent. Methods In two cross-sectional studies in Zambia in 2024, we genotyped the artemisinin resistance-associated gene Pfkelch13. In Kaoma, western Zambia, we evaluated the percentage of patients with day-3 parasite positivity following treatment with artemisinin-based combination therapy, and ex vivo parasite susceptibility to dihydroartemisinin (the active metabolite of artemisinin). We also assessed longitudinal changes in Pfkelch13 mutation prevalence in Kaoma using isolates collected from 2018 through 2026. Results We identified a novel mutation, Pfkelch13 A724E, in 52% (113 of 217) of isolates from Western Province, 51% (94 of 184) of isolates from North-Western Province, and 11.7% (229 of 1,949) of isolates country-wide. In Kaoma, 28% (21 of 75) of patients carrying Pfkelch13 A724E mutant parasites before treatment were parasite positive on day 3, compared with 0% (0 of 23) of patients with the wild-type allele (P=0.003). Within day-3 positive patients, the proportion of A724E mutant parasites increased significantly after treatment (P = 0.013). The prevalence of Pfkelch13 A724E in Kaoma increased steadily from 0% (95% confidence interval [CI], 0 to 22%) in 2018 to 79% (95% CI, 73 to 85%) in 2026. Conclusions A novel Pfkelch13 mutation conferring partial resistance to artemisinin is spreading in Zambia. Additional clinical evaluations are urgently needed in the region. (Funded by the Gates Foundation, INV-048316).

Background: Isoniazid resistance is the most common form of drug-resistant tuberculosis (TB) globally. However, WHO-recommended molecular tests available to most TB patients worldwide detect rifampin resistance only, risking under-treatment of isoniazid-resistant, rifampin-susceptible TB (HR-TB) and subsequent emergence of rifampin resistance. Methods: This prospective study (2020-2024) aimed to collect and archive sputum specimens from all adults diagnosed with rifampin-susceptible pulmonary TB in Ho Chi Minh City, Vietnam. Cases were participants who developed rifampin-resistant recurrence; controls had rifampin-susceptible recurrence or no recurrence. Whole-genome sequencing of paired isolates distinguished acquired rifampin resistance from reinfection. The effect of pre-existing isoniazid resistance on rifampin resistance acquisition was estimated using inverse probability of treatment weighting, and the projected epidemiological impact of routine HR-TB testing was modelled. Results: 42,843 people were diagnosed with TB during the study period, from whom we archived 33,843 sputum samples. We enrolled 1,241 participants, 873 (70.4%) of whom had analysable data. 51/873 (5.8%) acquired rifampin resistance, of whom 49/51 (96.1%) had undetected isoniazid resistance. The weighted risk of acquired rifampin resistance was 2.98% (95% CI 2.08-4.50) with undetected isoniazid resistance, versus 0.03% (0.00-0.08) without (risk ratio105.42 (33.43-309.69)). Modelling projected that universal HR-TB diagnosis and treatment would reduce RR-TB incidence by 46% (35-61) over 10 years in Vietnam, with reductions of 26% (12-43) projected even where HR-TB prevalence was as low as 5%. Conclusions: Undetected, under-treated HR-TB confers a 100 fold increased risk of acquiring rifampin resistance. Routine isoniazid susceptibility testing combined with effective HR-TB treatment could substantially reduce the burden of RR-TB.

Infectious bursal disease virus (IBDV) and H9N2 avian influenza virus (AIV) are significant global threats to poultry health and production. While IBDV induces severe immunosuppression, undermining host defense and vaccine efficacy, H9N2 AIV is characterized by widespread prevalence, persistent shedding, and substantial economic losses. Conventional inactivated vaccines often fail to elicit robust cellular immunity and necessitate multiple booster doses, underscoring the urgent requirement for advanced multivalent vaccination platforms. To address this, we developed a recombinant herpesvirus of turkey (rHVT BAC-VP2-HA) using a bacterial artificial chromosome (BAC) vector system, engineered to co-express the major protective antigen VP2 of IBDV and the hemagglutinin (HA) of H9N2 AIV. Genetic stability and in vitro characterization confirmed that the recombinant exhibited replication kinetics and plaque morphology comparable to parental HVT, with stable antigen expression. In SPF chickens, rHVT BAC-VP2-HA induced strong humoral immune responses against both target antigens, comparable to those elicited by a commercial inactivated vaccine. Crucially, the recombinant virus significantly enhanced cellular immunity, evidenced by markedly elevated CD3+CD8+ T cell responses. Upon challenge, the recombinant conferred high clinical protection (86%) against virulent IBDV, significantly ameliorating bursal pathology and reducing viral loads. Notably, it provided complete (100%) protection against H9N2 AIV, effectively abolishing viral shedding and suppressing viral replication in respiratory tissues. These results demonstrate that rHVT BAC-VP2-HA is a safe and efficacious candidate capable of eliciting humoral and cellular immune responses, offering a promising strategy for the integrated control of major poultry diseases. ImportanceInfectious bursal disease virus (IBDV) and H9N2 avian influenza virus (AIV) are major pathogens that frequently co-circulate in poultry, where IBDV-induced immunosuppression compromises the efficacy of vaccination against other infectious diseases. Conventional inactivated vaccines primarily induce humoral immunity and are often insufficient to prevent viral shedding or provide broad protection against multiple pathogens. In this study, we developed a recombinant herpesvirus of turkeys (HVT) vaccine co-expressing the IBDV VP2 and H9N2 HA antigens and demonstrated that it induces both robust antibody responses and enhanced CD8+ T cell immunity. Notably, this vaccine not only provided effective protection against IBDV but also completely prevented viral shedding following H9N2 challenge. These findings highlight the advantage of HVT-vectored multivalent vaccines in eliciting balanced immune responses and controlling virus transmission, providing important insights for the development of next-generation vaccines against immunosuppressive and respiratory viral co-infections in poultry.

West Nile virus (WNV) and Usutu virus (USUV) are neurotropic Orthoflaviviruses sharing a similar enzootic transmission cycle primarily involving Culex pipiens mosquitoes as vectors and birds as amplifying hosts. First identified in Africa, both viruses established endemicity across Europe over the past two decades, most likely introduced and spread by migratory bird species along Mediterranean flyways. In avian species, infection outcomes range from subclinical to fatal neuroinvasive disease, varying by viral strain, host immunity, and species susceptibility. Southern France emerges as a key hotspot for the circulation of these viruses, supported by diverse avian habitats conducive to year-round viral maintenance. This study investigated the prevalence of WNV and USUV in more than 2500 sedentary and migratory wild birds from these regions during 2024-2025 using molecular surveillance. Samples were collected using mist net and bird boxes, across multiple passerine and non-passerine taxa, spanning wetlands, urban fringes, and agricultural zones. Our analyses revealed widespread viral circulation across diverse species, mainly among passerines such as great tits, house sparrows, and barn swallows with USUV detected at higher rates than WNV in both study years. Overall prevalence was markedly higher in 2024 than in 2025, potentially reflecting climatic or ecological drivers. Migratory individuals likely seed viral introductions during seasonal passages, whereas resident populations sustain local enzootic cycles, facilitating overwintering persistence. These results highlight the pivotal role of mixed avifauna in arbovirus dynamics within Mediterranean Europe and emphasize the necessity for integrated, year-round surveillance targeting high-risk species and habitats. Enhanced monitoring will aid in predicting spillover risks and informing vector control strategies to mitigate zoonotic threats.

Ebola virus disease (EVD), caused by the Ebola virus (EBOV), is characterized by high morbidity and mortality, with 16 distinct EVD outbreaks reported in the Democratic Republic of the Congo (DRC), alone. As part of the formal response to the 2018 outbreaks in Equateur and North Kivu provinces, a recombinant vesicular stomatitis virus-Zaire Ebolavirus envelope glycoprotein vaccine (rVSV-ZEBOV-GP) vaccine was deployed under emergency use. While clinical trials have evaluated vaccine safety and efficacy, there is a paucity of real-world data documenting antibody durability for longer periods post-vaccination. Here, we present serologic data from 1081 individuals in Beni, North Kivu (n = 599) and Mbandaka, Equateur (n = 482) who were vaccinated during the outbreaks--with samples from baseline up to five-years following vaccination. Using a multiplexed immunoassay, we show sustained anti-EBOV GP reactivity: at year-5 collection, 72% of individuals naive at time of vaccination remained seroreactive to EBOV GP. Stratifying by site, antibody titers remained significantly elevated after baseline across all post-vaccination timepoints in both linear and logistic mixed-effects models. Pre-existing EBOV GP reactivity at baseline was the strongest independent predictor of antibody response in Mbandaka, associated with higher titers and greater odds of seropositivity (OR = 3.87, 95% CI: 2.50-6.01, p-value < 0.001), consistent with a boosting effect among previously exposed individuals. However, this was not replicated in Beni (OR: 0.66, 95% CI: 0.27-1.58, p-value = 0.348). In Mbandaka, among those recipients who reported receiving a booster dose, the odds of seroreactivity were 12.75-fold (p-value < 0.001) and 3.68-fold higher (p-value = 0.04) at 4.2 and 5-years post-vaccination, respectively, in comparison to odds of reactivity at three weeks following administration of the initial dose. Occupational groups with zoonotic or community-level exposure had trending lower odds of seroreactivity relative to healthcare workers, most consistently in Beni. Ultimately, these data indicate that five years following administration of the rVSV-ZEBOV-GP vaccine, most vaccinated individuals retain detectable anti-EBOV GP antibodies. While correlates of protection for EVD are not well established, sustained IgG seroreactivity to EBOV GP may serve as a marker for future understandings of the durability of and variation in immune responses to this high-consequence pathogen.

The multinational Andes virus outbreak linked to the MV Hondius has exposed contacts across several countries, but the absence of further confirmed cases remains difficult to interpret given the long incubation period. We estimate the probability that secondary clusters may emerge using a stratified branching-process model parameterized with country-level tracing and isolation indicators. The risk of sustained spread is low, but secondary clusters remain plausible under imperfect isolation or pre-symptomatic transmission. These results support coordinated contact tracing and effective isolation while exposed contacts remain within the risk window.