New England Journal of Medicine

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.

Background: Monoclonal antibodies have emerged as a prophylactic strategy to prevent symptomatic SARS-CoV-2 infection in immunocompromised individuals. However, the evolutionary and clinical implications of breakthrough infections under this regime remain unclear. Methods: A male in their 80s with a haematological/oncological diagnosis received a 2000 mg intravenous infusion of sotrovimab in March 2023 and was diagnosed with COVID-19 by RT-qPCR from a nasopharyngeal swab in August 2023. Weekly samples (n=24) were collected through February 2024 (171 days). All samples underwent whole-genome sequencing, with select mutations subjected to functional assessment. Findings: Sequencing identified the GE.1 lineage at all timepoints. An intra-host recombination event in ORF1ab (positions 8942-12458) was detected prior to 23 weeks post-detection, followed by a 14-fold increase in viral load (7.42e+06 to 1.00e+08 RNA copies/mL) and a marked shift in the viral population. E340D, a sotrovimab resistance mutation, was detected at low abundance (46%) within the first week post-infection, fluctuated over time, and was nearly fixed by week 15 (107 days) post-detection. We assessed five spike mutations - V36M, S98F, and V213G in the N-terminal domain, Y505P in the receptor-binding domain, and P681Q near the S1/S2 cleavage site - and additionally evaluated the impact of E340D. V36M conferred the highest infectivity across all cell lines, with the most significant effect in low-TMPRSS2 cells. While all mutations showed enhanced infectivity with the addition of E340D, the effect was most pronounced in mutations with lower baseline infectivity. The addition of E340D significantly decreased relative neutralizing titres for V36M, S98F, and V213G, enabling escape from neutralizing antibodies in XBB-responsive individuals, illustrating an enhanced phenotypic advantage. Patient neutralizing activity was absent pre-sotrovimab, and sotrovimab-induced neutralization was further compromised by selection of E340D. Interpretation: Sotrovimab pre-exposure prophylaxis in an immunocompromised patient did not prevent SARS-CoV-2 infection, and selected for resistant mutation E340D, with unexpected fitness consequences across non-receptor binding domain spike regions.

Background: Invasive non-typhoidal Salmonella (iNTS) disease causes an estimated 605,000 cases and 76,000 deaths each year, concentrated in sub-Saharan Africa, where the African Salmonella Typhimurium sequence type 313 (ST313) lineage predominates. Vaccine development is hampered by an absence of efficacy data and undefined correlates of protection. Methods: We conducted a phase 1, randomised, double-blind, dose-escalation controlled human infection model (CHIM) in healthy UK-resident adults, who were randomly assigned 1:1 to oral challenge with S. Typhimurium 4/74 (ST19, associated with gastrointestinal disease) or D23580 (ST313, associated with invasive disease). Dose-escalation was guided by a Bayesian continual reassessment method (CRM). The primary endpoint was Salmonella diagnosis, defined as sustained fever [≥]38{degrees}C on [≥]2 occasions [≥]12 hours apart and/or bacteraemia. Trial registration ClinicalTrials.gov (NCT05870150). Findings: Between August 2023 and December 2024, 50 participants were enrolled (25 per strain). 105 CFU was the maximum feasible dose, with CRM-estimated attack rates of 57.9% (95% credible interval 37.3 - 73.8) for D23580 and 47.4% (26.7 - 65.7) for 4/74. There were no serious adverse events. We found no clinical, microbiological, or immunological difference between the two pathovariants. Higher baseline serum anti-O-antigen IgG was associated with reduced disease (adjusted OR 0.42, 95% CI 0.17 - 0.90) and higher baseline faecal anti-lipopolysaccharide IgA with reduced colonisation (OR 0.12, 95% CI 0.01 - 0.59). Interpretation: This S. Typhimurium CHIM is safe, reproducible, and provides a platform to generate early efficacy signals and candidate correlates of susceptibility, thereby de-risking future iNTS vaccine trials. The absence of a phenotypic difference between the invasive and gastrointestinal pathovariants in immunocompetent adults suggests that host factors, rather than pathogen adaptation alone, shape the invasive phenotype seen in endemic settings. Funding: Wellcome Trust.

Background Despite widespread vaccination, pertussis remains a poorly controlled disease globally and results in substantial annual morbidity and mortality, particularly in young children. Controlled human infection models (CHIMs) using the causative agent Bordetella pertussis are promising systems to enable the study of pertussis disease pathogenesis and immunology and to rapidly assess vaccines and therapeutics. While a pertussis CHIM that produces asymptomatic infection has been established in Europe, the development of a CHIM that leads to symptomatic illness would be advantageous for evaluating vaccine efficacy against both infection and disease. Methods Healthy participants 18-40 years of age were inoculated intranasally with one of eight doses (ranging from 104 to 108 colony forming units (CFU)) of the pertactin-producing B. pertussis isolate D420 at the challenge facility within the Canadian Center for Vaccinology (Nova Scotia, Canada). The study occurred in two stages. In stage one, the B. pertussis dose was escalated in cohort groups of five to six participants until reaching an endpoint where 70-90% of participants exhibited mild (non-severe, Grade 1 or 2) symptomatic infection, defined as the Human Infectious Dose 70-90 (HID70-90). In stage two, additional challenges were conducted for doses below, at, and above the identified HID70-90 to characterize the emerging pertussis model. For all challenge doses, participants were closely monitored during an inpatient stay of up to 24 days and post-discharge for laboratory-confirmed infection, pertussis symptoms, safety, and IgG antibody responses to four B. pertussis antigens including pertussis toxin, filamentous hemagglutinin, fimbriae, and pertactin. All participants received a five-day course of azithromycin, where timing of initiation depended on B. pertussis testing and symptoms. The study was conducted between July 4, 2022 and March 19, 2025. Findings Seventy-five participants were inoculated with one of the eight B. pertussis D420 challenge doses and completed the inpatient stay. From the stage-one dose escalation, we found that 107 CFU of B. pertussis D420 was the lowest dose that achieved the HID70-90, where 9 of 12 participants (75.0%) exhibited mild symptomatic infection. Following stage-two challenges, 16 of 22 total participants at 107 CFU (72.7%) developed mild symptomatic infection, thus verifying the HID70-90. The symptomatic infection rate below the HID70-90 at 5x106 CFU of D420 was 20.0% and above the HID70-90 at 5x107 and 108 CFU were 58.3% and 55.6%, respectively. Symptoms with elevated frequency for symptomatic infection (relative to background symptoms in non-infected) included nasal congestion, runny nose, fatigue, malaise, and cough. At the HID70-90, 50% of symptomatic infections included cough. Serological analyses of the four highest (stage-two) challenge doses (5x106, 107, 5x107, 108 CFU) revealed that antibody titres increased over time post-challenge. Seroconversion for at least one of the four studied antibodies was nearly twice as common for symptomatic (70.0%) than asymptomatic (35.7%) infection and was absent (0%) for non-infected. All infections were cleared following azithromycin treatment (100%) and there were no study-related serious adverse events. Interpretation A safe and reproducible symptomatic pertussis CHIM was achieved, providing a model for research on pertussis disease pathogenesis and immunology and for assessing vaccines and therapeutics. (Clinicaltrials.gov, NCT05136599).

Introduction: Anaemia and micronutrient deficiencies are common in low- and middle-income countries, where vaccine-induced immune responses are often suboptimal. However, whether pre-vaccination nutritional status influences pneumococcal vaccine immunogenicity in young children remains poorly characterised. Methods: We examined associations between pneumococcal vaccine responses in 670 Kenyan children enrolled in three vaccine trials: PRISM (PCV10; n=195; NCT01028326), FPCV (fractional- and full-dose PCV10/PCV13; n=306; NCT03489018), and PATH-wSP (whole-cell pneumococcal vaccine; n=169; NCT02543892) and baseline anaemia (FPCV and PATH-wSP) and micronutrient status (iron, folate, zinc, and vitamins A, B12, D, and E). Analyses were performed separately for each trial. Primary outcomes were post-vaccination serotype- or antigen-specific IgG concentrations, opsonophagocytic activity (OPA) titres, and composite IgG or OPA z scores. Results: Vitamin B12 and haemoglobin concentrations were positively associated with composite and serotype- or antigen-specific antibody responses in analyses controlling for age, sex, malnutrition and inflammation. In the PRISM trial, PCV10-induced IgG (serotypes 1 and 6B) and OPA (serotypes 1, 4, 14, and 23F) responses were positively associated with vitamin B12 concentrations. Moderate anaemia was associated with lower IgG responses to serotypes 9V and 14 following full-dose PCV13 vaccination (FPCV) and lower antigen-specific IgG responses following the 1 mg PATH-wSP vaccine. No consistent associations were observed for ferritin, folate, zinc, or vitamins A, D, and E. Conclusion: Vitamin B12 deficiency and anaemia were associated with reduced pneumococcal vaccine responses in young Kenyan children. Optimising nutritional status before vaccination could be a strategy to improve vaccine responses in populations where anaemia and micronutrient deficiencies are common.

Abstract The association between COVID-19 vaccination and Guillain-Barre syndrome (GBS) has been previously investigated with inconsistent results, largely due to limited data and lack of concurrent controls. To address this problem, a large longitudinal cohort study was conducted using National COVID Cohort Collaborative (N3C) data. While COVID-19 infection was associated with increased GBS occurrence, COVID-19 vaccination was associated with significantly reduced GBS risk relative to unexposed (unvaccinated and uninfected) control, corresponding to a 61% lower 30-day risk (incidence risk ratio: IRR = 0.39, P < 0.01), consistent with multivariable Cox regression showing a similar reduction (adjusted hazard ratio: aHR = 0.41, P < 0.01). This protective association was observed only among recipients of mRNA vaccines (BNT162b2: IRR = 0.38, P < 0.01; mRNA-1273: IRR = 0.24, P < 0.01), but not among recipients of adenoviral-vector vaccines (IRR = 1.38, P > 0.05). Prior COVID-19 vaccination also reduced infection-associated GBS risk. Additional factors associated with GBS risk included sex, vaccine dose, and pre-existing comorbidities such as stroke, neurological disorders, and autoimmune diseases. Overall, our N3C large-scale study provides evidence that COVID-19 mRNA vaccination reduces GBS risk, supporting the safety profile of mRNA vaccines and warranting further mechanistic investigation.

The stall in clinical translation of extracellular vesicle (EV) therapeutics requires addressing critical and hidden causes of attrition and delays. Despite more than 150 registered clinical trials and fifteen years of clinical investigation, small EV (sEV) therapeutics have yielded zero FDA approvals, a translational deficit that has received remarkably little quantitative scrutiny. We systematically evaluated 783 EV-related clinical trials (152 of which therapeutic) registered through December 2025, benchmarking the sEV pipeline against 1,131 CAR-T cell therapy trials (ex-China) that share the "process is the product" manufacturing constraint, yet have delivered six FDA-approved products. A quality-failure paradox emerges, in which industry-sponsored sEV trials exhibit 39% higher composite methodological quality (quality index 2.49 vs. 1.79) yet fail at approximately five-fold the rate of academic programmes (28.6% vs. 5.1%; OR=7.40, 95% CI 2.5-22.3, p=0.0004). Cross-modality replication in CAR-T trials confirms the direction of this association (OR=2.51, p<0.001; Cochran-Mantel-Haenszel pooled OR=2.76, p<0.001). Registry abandonment, affecting 24% of academic sEV trials, constitutes a hidden failure mode that, when reclassified, dissolves the apparent paradox. Premature clinical entry of incompletely defined products, rather than insufficient methodological rigour, represents the central constraint on sEV translational progress. The opacity of research data, inadequate clinical evaluation, and failure to report negative (null) findings in clinical trials create a hidden crisis that drains hundreds of millions invested by public and private sector-eroding the return on investment-and traps progress in cycles of duplicated effort, wasteful resource allocation, and missed learning opportunities.

Background Mupirocin, a widely used topical agent for decolonization of Staphylococcus aureus, is increasingly compromised by resistance. Although plasmid-mediated mupirocin resistance is a recognized cause of decolonization failure, its role in facilitating hospital-wide transmission is unknown. Methods We conducted genomic surveillance of S. aureus at two interconnected urban hospitals where mupirocin decolonization is routine. Genome sequencing of >10,000 isolates was integrated with patient data to identify transmission and resistance determinants. Bacterial phenotypes and fitness were evaluated in vitro and in murine colonization models. Findings Genome sequencing identified 475 hospital transmission events; none were detected by conventional surveillance. The mupA (ileS2) resistance determinant, carried on conjugative plasmids, was enriched eightfold in methicillin-resistant S. aureus (MRSA) relative to methicillin-susceptible strains. mupA was associated with nearly a threefold greater chance of hospital transmission, especially within endemic healthcare-associated MRSA lineages, and was enriched twofold in hospital-onset infections compared with admission colonizing isolates. Multiple independently evolved inactivating mutations in the essential chromosomal gene ileS1 co-occurred with mupA, creating plasmid addiction in which mupA became indispensable for bacterial survival. Addiction arose most frequently within the dominant community-acquired MRSA lineage, where plasmid carriage reduced colonization fitness in mice. Plasmid-containing strains exhibited stringent-response activation, explaining the fitness costs and collateral tolerance to disinfectants, such as ethanol and peroxide. Although addiction reduced S. aureus fitness, it increased plasmid transfer, and addicted variants spread across hosts, demonstrating adaptation that mitigates these costs. Unexpectedly, we identified a mupirocin-dependent vulnerability to isoleucine limitation, revealing a potential strategy to target mupA-mediated resistance. Interpretation Plasmids promote hospital transmission of mupirocin-resistant S. aureus and create an evolutionary trap in which antibiotic use selects for bacterial dependence on otherwise costly resistance elements. This dependence revealed a collateral bacterial vulnerability that could be exploited to target resistant strains and preserve the effectiveness of mupirocin.

Objectives: To compare the effectiveness of povidone-iodine ear wash compared to no ear wash and oral cotrimoxazole compared to placebo given in addition to standard topical antibiotic treatment (ciprofloxacin drops) for chronic suppurative otitis media (CSOM) in Australian Aboriginal children. Methods: A randomised, parallel, 2 x 2 factorial design, assessor-blinded clinical trial in the remote Northern Territory of Australia. Aboriginal children with confirmed CSOM were eligible to be randomised into four treatment groups, allowing two primary treatment comparisons in a 2-in-1 trial approach. Participants received standard treatment (twice daily cleaning and topical ciprofloxacin drops) plus: i) either 16 weeks of pre-treatment povidone-iodine ear wash or no povidone-iodine ear wash; and ii) either 16 weeks of oral cotrimoxazole or placebo. Central randomisation with allocation concealment and triple-blinding of the oral antibiotic treatment arms was used. The relative risk (RR) and risk difference (RD) were estimated after adjustment for age, community, and the other intervention. The primary outcome was the proportion of children with any otorrhoea (clinical failure) after 16 weeks of treatment. Secondary outcomes included size of tympanic membrane (TM) perforation and amount of discharge, time to cessation of discharge, proportion of children with respiratory and other pathogens in ear discharge (at baseline and 16 weeks) and hearing levels (at 12 months). Findings: 280 children with CSOM were randomised and 270 had their primary outcome assessed. Clinical failure (presence of any ear discharge) after 16 weeks of treatment was 66/134 (49%) in the povidone-iodine group versus 69/136 (51%) in the no povidone-iodine group (RD= -1% (-12,11), p= 0.93) and 56/134 (42%) in the cotrimoxazole group versus 79/136 (58%) in the placebo group (RD=-16% (-28,-4), p=0.007). The amount of discharge, TM perforation size, the level of hearing impairment, and serious adverse events were not significantly different in both treatment comparisons. Anaerobic growth (24%), Pseudomonas aeruginosa (21%) and Haemophilus influenzae (17%) were the most common pathogens found in the ear discharge before treatment. Fungi or yeast (24%), Staphylococcus aureus (15%), and anaerobic growth (10%) were the common pathogens after 16 weeks of treatment, with no significant differences between groups. At 12 months post-randomisation, 55-60% of children had at least one discharging ear and there was no difference between treatment groups. Interpretation: Povidone-iodine ear washes did not contribute to better ear outcomes in this study. Cotrimoxazole for 16 weeks resulted in more children with clinical improvement to dry ears. Oral cotrimoxazole may play a role in reducing the burden of CSOM in populations with high rates of persistent disease.

Background. The course of a pandemic depends on viral traits, available public health interventions, implementation, and individual behavior, all of which interact and vary over time and space. Understanding COVID-19 therefore requires considering these factors together. Methods. National mortality, state-level mortality per 100,000 population for four representative states, policy stringency, and vaccination coverage were assembled from publicly available sources for February 2020 through September 2022. Viral traits, mutation rates, and vaccine effectiveness were drawn from published systematic reviews and standardized relative to wild-type values. Results. Each state experienced a different worst wave, separated by as much as 18 months, with up to a 24-fold difference in state mortality during major waves. NPI stringency was initially high and responsive to COVID waves, but declined during 2021 in both magnitude and responsiveness as vaccination levels rose, then flattened. Viral evolution first increased transmissibility; as population immunity rose, immune escape increased sharply, particularly with Omicron, which produced similar mortality peaks in all four states and the second largest national peak. Conclusions. COVID-19 did not unfold as a single national pandemic but as regionally divergent epidemics that fragmented public perception and weakened cohesion. At the same time, SARS-CoV-2 evolved traits that reduced the apparent and actual effectiveness of interventions. Omicron brought these processes together: despite producing one of the largest national mortality waves, it elicited little renewed policy activation or booster uptake. I describe this progressive uncoupling of epidemic threat, intervention effectiveness, policy activation, and public compliance as Acquired Social Immune Dysfunction.

Pneumococcal vaccination of older adults is primarily guided by age and clinical eligibility, despite substantial variation in individual risk of severe pneumonia. Here, we used longitudinal electronic health records from 787,538 adults aged [&ge;]65 years to evaluate the real-world effectiveness of the 20-valent pneumococcal conjugate vaccine (PCV20) and quantify clinical benefit according to baseline risk of pneumonia hospitalization. We developed and validated a machine-learning model using pre-PCV20 data to estimate individual 12-month hospitalization risk and integrated these predictions into a propensity score matching framework. Overall vaccine effectiveness against pneumonia hospitalization was 16.5% (95% CI, 10.6-22.1), but this population-level estimate masked substantial heterogeneity in clinical benefit. The 60% at lowest predicted risk, characterized by younger age and fewer pulmonary and other chronic conditions, showed no measurable reduction in hospitalization (VE, 3.1%; 95% CI, -14.4 to 18.0) and had an estimated 1-year number needed to vaccinate (NNV) of 7,423, compared with 184 and 115 in the intermediate- and high-risk groups, respectively. These findings suggest that incorporating baseline risk into adult pneumococcal vaccination strategies could enable more targeted and potentially better-timed vaccination.

Importance: Pharmacological targeting of host mechanisms that limit sepsis-induced organ dysfunction represents a new therapeutic approach. Preclinical studies showed that low-dose epirubicin enhances tissue damage control and attenuates sepsis severity independently of pathogen burden, thereby promoting disease tolerance to infection. Yet epirubicin can cause myelotoxicity when used in cancer therapy. Objective: To investigate whether low-dose epirubicin can safely be administered to patients with sepsis and septic shock. Design, Setting, and Participants: A randomized, double-blind, placebo-controlled clinical trial conducted in five German University hospitals. Patients with sepsis, defined by Sepsis-3 criteria, were eligible within 48 hours after diagnosis. The first patient was enrolled on October 19, 2022, and the last follow-up was conducted on May 21, 2025. Interventions: Eligible patients were randomized in a 4:1 ratio to receive either placebo or low-dose epirubicin in addition to standard care. There were three consecutive phases. Patients in the epirubicin group received a single dose of epirubicin (either 3.75 mg/m2, 7.5 mg/m2 or 15 mg/m2, depending on study phase). Main Outcomes and Measures: The primary endpoint of the trial was the 14-day myelotoxicity. Secondary and explorative outcomes included 90-day mortality, the degree of organ dysfunction as assessed by SOFA score, PK/PD modelling and cytokine release. Results: Of 854 patients assessed for eligibility, 32 were randomized and 31 were included in the primary analysis population. Six participants received placebo, nine participants received 3.75 mg/m2, nine received 7.5 mg/m2 and eight individuals received 15 mg/m2 epirubicin, respectively. There was no myelotoxicity in any group. Mortality at 90 days and SOFA-scores were not significantly different between groups. Two of 39 SAEs in the epirubicin group were assessed by the investigators as possibly related to epirubicin, Conclusions and Relevance Among patients with sepsis and septic shock, low dose epirubicin was not associated with increased myelotoxicity.

We used a stochastic simulation model to estimate the effectiveness of combined exit and entry airport screening for Bundibugyo ebolavirus disease (BVD), using natural-history parameters from a Bayesian re-analysis of the 2012 Isiro outbreak. For a 12-hour international flight from DRC or Uganda at 86% screening sensitivity, we estimate 65% of infected travellers would arrive undetected (95% CrI: 38 - 76%). The main driver of this outcome is the relative duration of the the incubation period (approximately 7.7 days) and the onset-to-severe-disease interval (approximately 4 days): most infected travellers board before symptom onset and are undetectable by any syndromic screen, whilst those who are symptomatic progress rapidly to illness severe enough to preclude travel. This is compounded during active epidemic growth, when recently exposed (and therefore pre-symptomatic) cases are overrepresented among travellers. Syndromic airport screening offers limited protection against BVD spread via air travel, and should be complemented by outbreak control at source and strengthened clinical surveillance in receiving countries with high travel connectivity to affected areas.

We compared the immunogenicity of three licensed egg-based inactivated influenza vaccines, including TetrAnflu (Sinovac quadrivalent), Fluarix Tetra (GSK quadrivalent), and Vaxigrip (Sanofi trivalent), in adult healthcare workers in Hong Kong during the 2025/26 season. Paired pre- and post-vaccination sera from age- and sex-matched recipients (n=30 to 40 per group) were tested by hemagglutination-inhibition assays against vaccine strains. After adjustment for age, sex, and sampling interval, the vaccines induced broadly comparable rises in antibody titers, proportions achieving titers >=40, and seroconversion rates, with a superior response to A(H1N1) after TetrAnflu. These real-world findings support the interchangeability of these vaccines for influenza vaccination programs.

Brazil bears one of the largest chikungunya burdens in the Americas (more than 1.2 million confirmed cases since 2014), and the 2024-25 wave expanded further south than any prior outbreak. IXCHIQ entered Sistema Unico de Saude (SUS) deployment in February 2026 despite an August 2025 US FDA biologics license suspension over serious adverse events in adults aged 60 years and older; regulatory authorities in the EU (EMA), Brazil (ANVISA), and Canada maintained licensing with revised prescribing guidance requiring individual benefit-risk assessment. Evidence to guide rollout targeting is lacking. We analyzed 1,235,424 confirmed chikungunya cases reported to Sistema de Informacao de Agravos de Notificao SINAN (2015-2025) across 5,570 municipalities. A Bayesian hierarchical spatiotemporal model quantified spatial structure and persistence of transmission across municipalities, controlling for national arboviral co-circulation trends. Disease progression was assessed with Cox models stratified by age and sex. Municipal 2024-25 incidence rate ratios and proportions aged 65 years or older (tertiles) defined transmission-control, clinical-preparedness, and combined-priority municipalities. Transmission epicenters shifted from the Northeast (2016-17) to the Central-West (2024-25; peak municipality IRRs >2.7 times the national median); clustering and seasonality persisted. Cases concentrated among adults aged 25 to 55, while post-hospitalization mortality rose steeply with age (HR 10.57, 95% CI 7.64-14.62 for ages 80 years and older versus adults aged 20 to 29). Males had faster progression to hospitalization (HR 1.26) and death (HR 1.76, onset to death) despite fewer notifications. The Central-West led transmission yet had lower case fatality among hospitalized cases (3.54%, 81 deaths out of 2,285 hospitalized) than the Southeast (4.95%, 163 deaths out of 3,291 hospitalized), reflecting demographic rather than purely clinical differences between regions. A municipality-level allocation framework classified 832 municipalities as transmission-control priority (high recent transmission, younger population; predominantly Central-West), 832 as clinical-preparedness priority (lower transmission, older population; predominantly Southeast and South), and 461 as combined-priority (high on both dimensions; predominantly Northeast and Southeast). Chikungunya transmission and mortality are spatially decoupled in Brazil: regions driving epidemic expansion (Central-West) are not those bearing the highest case fatality (Southeast). An age-only vaccination allocation rule would leave 82% of 2024-25 reported cases in municipalities it would not prioritize. A rule that targets only older adults without accounting for geography is likely to miss the municipalities where transmission is actively expanding. A dual-axis framework addressing both dimensions is required for the SUS rollout.

Background: Live oral rotavirus vaccines were found to be less effective in low-income countries compared to high-income countries when using the same product and dosing schedule. We investigated whether altering dose timing may improve immune protection using a target trial emulation approach. Methods: We emulated a target trial with clone-censor weighting to compare the effectiveness of the recommended 2-dose rotavirus vaccine schedule with a delayed schedule among children under two years of age in Peru and Brazil. Secondary data from the Malnutrition and Enteric Disease Study (MAL-ED) birth cohort (2009-2014) were analyzed. Children were followed from the date of birth until the earliest occurrence of a rotavirus outcome (infection confirmed by PCR or enzyme immunoassay (EIA) or diarrhea confirmed by EIA), protocol nonadherence, loss to follow-up, or their second birthday. Results: We included 154 children in Brazil and 192 in Peru. At two years of follow-up, the risk ratio (RR) for PCR-confirmed infection, using the recommended schedule as the reference, was 1.00 (95% confidence interval [CI]: 0.73-1.37) in Peru and 0.85 (95% CI: 0.31-1.66) in Brazil. In Peru, the delayed schedule was associated with a higher cumulative risk of EIA-confirmed rotavirus diarrhea (RR at two years: 1.73; 95% CI: 1.02-2.77). Conclusions: Delaying the two-dose rotavirus vaccine schedule did not change the cumulative risk of rotavirus infection, but the delayed schedule was associated with a higher risk of rotavirus diarrhea in Peru, where rotavirus incidence was higher.

Rationale. Guidelines disagree on antibacterial treatment for adults with community-acquired pneumonia and a positive respiratory viral test, particularly hospitalized patients and outpatients with comorbidities. Objectives. To estimate associations between antibacterial treatment selected for community-acquired pneumonia and outcomes in adults with virus-positive, imaging-evaluated nonsevere pneumonia. Methods. We conducted a retrospective multicenter study using Epic Cosmos data from 2016-2025. Hospitalized patients treated empirically by 24 hours were compared by continuation during hours 24-48; outpatients were compared by prescription at emergency-department discharge. Analyses were stratified by guideline-defined comorbidity and used propensity-score overlap weighting with source-cluster bootstrap confidence intervals. Exploratory analyses assessed respiratory virus, antiviral treatment, antibacterial class, and outpatient timing. Measurements and Main Results. The cohort included 376,320 adults: 275,604 inpatients and 100,716 outpatients. Inpatients who continued treatment had higher 30-day adverse-event risk without guideline comorbidity (adjusted risk difference, 1.70 percentage points; 95% confidence interval, 0.80-2.39) and with guideline comorbidity (2.56; 1.88-3.14), and longer post-landmark stay (adjusted mean ratios, 1.14 and 1.08). Exploratory class-specific analyses showed the largest adverse-event and mortality associations with broad therapy targeting resistant staphylococci or Pseudomonas; macrolide-containing and other atypical coverage showed no consistent adverse signal. Outpatient prescribing was associated with lower risks, but care-transition and residual confounding remained. Conclusions. Continued inpatient therapy after the empiric period showed no evidence of benefit and was associated with worse observed outcomes. Outpatient associations favored prescribing but remained vulnerable to care-transition and residual confounding.

Importance: Avacopan is a small-molecule C5aR1 antagonist used as adjunctive treatment for granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). Evidence of real-world clinical effectiveness and safety is limited. Objective: Compare effectiveness and describe safety outcomes of avacopan plus SoC versus SoC alone. Design: Retrospective U.S. cohort study with prevalent new-user design emulating sequential nested trials with up to 12-month follow-up. Index dates: first avacopan prescription (avacopan arm); first rituximab or cyclophosphamide claim (SoC arm) during trial window. Setting: Optum Market Clarity administrative claims (October 2015 - June 2025). Participants: Adults receiving rituximab or cyclophosphamide after newly diagnosed or relapsing GPA/MPA. Comparative effectiveness cohort: patients meeting baseline eligibility. Safety cohort: adults with an avacopan prescription, regardless of other eligibility. Interventions: Avacopan plus SoC vs SoC alone. Main Outcomes and Measures: Relapse, prednisone-equivalent daily dose (PEDD) [&le;]7.5 mg, and serious hepatic event hospitalization were prespecified, whereas cumulative oral glucocorticoid exposure was analyzed post-hoc. A strict hepatic-event screen required [1] acute/subacute hepatic failure, central hemorrhagic liver necrosis, or toxic liver disease and [2] [&ge;]1 code indicative of severe acute liver injury on the same claim; a relaxed hepatic-event screen required either criterion. Standardized mortality ratio and censoring weights accounted for baseline covariates and informative censoring. Treatment effects in the avacopan-treated population were estimated. Results: The effectiveness analysis included 183 avacopan and 4096 SoC index dates. The safety cohort had 828 avacopan users. There were 38 events of relapse in the avacopan arm and 956 in the SoC arm (weighted hazard ratio [95% CI]: 0.81 [0.59, 1.13]). PEDD [&le;]7.5 mg was numerically more common with avacopan plus SoC at most timepoints. Cumulative glucocorticoid exposure was lower with avacopan plus SoC; between-arm differences exceeded 500 mg from months 5 through 12. No avacopan-exposed patients met the strict hepatic event screen definition. Relaxed hepatic event screen events occurred in 2 (1.1%), 5 (0.6%), and 10 (0.5%) patients in the avacopan effectiveness, avacopan safety, and SoC cohorts, respectively. Conclusions and Relevance: Early evidence from claims data suggests avacopan plus SoC may reduce relapse risk and enable faster glucocorticoid tapering vs SoC alone. Serious hepatic events appear rare.

An uncontrolled and rapidly growing outbreak of Bundibugyo virus (BDBV) is currently gripping the Democratic Republic of the Congo and threatening health security across Central Africa. There are no available BDBV-specific vaccines, although emerging evidence suggests that the Ebola virus-specific vaccine, rVSV-EBOV (also known by its tradename ERVEBO), may offer cross-protective immunity. To directly address this question, we evaluated the efficacy of rVSV-EBOV in the uniformly lethal ferret model of BDBV infection. All vaccinated animals survived BDBV challenge and exhibited minimal clinical signs of infection, presumably as a result of a moderate--but protective--humoral immune response. These findings provide critical evidence further supporting the cross-protective efficacy of rVSV-EBOV, and they suggest a potential role for this vaccine in mitigating the ongoing BDBV outbreak.

BACKGROUND Current polio vaccines face challenges including vaccine-derived poliovirus and high-containment manufacturing. We evaluated a recombinant trivalent virus-like particle (VLP)-based poliovirus vaccine (VPV) for safety and immunogenicity in a first-in-human phase 1 trial. METHODS In this randomized, observer-blind, active-controlled trial, 72 healthy adults (18 to 54 years) were assigned (1:1:1:1) to receive a single dose of VPV at low (45:8:25 D-antigen units [DU] + 0.1 mg aluminum phosphate [AP]), medium (45:8:25 DU + 0.3 mg AP), or high (90:12:45 DU + 0.3 mg AP) doses, or conventional inactivated poliovirus vaccine (cIPV). Primary outcomes were safety and tolerability. Secondary outcomes included neutralizing antibody titers through day 180. RESULTS No serious adverse events or Grade 3 reactions were reported. Solicited adverse events were reported in 77.8%, 55.6%, and 72.2% of the low-, medium-, and high-dose VPV groups, respectively, and 66.7% in the cIPV group. By day 29, VPV induced dose-dependent neutralizing antibody responses. For serotypes 1 and 2, the high-dose VPV group achieved geometric mean titers (GMTs) of 73,582 (95% CI, 31,198-173,545) and 110,623 (95% CI, 59,276-206,451), respectively, comparable to cIPV at 45,161 (95% CI, 20,973-97,244) and 112,361 (95% CI, 58,280-216,625). Although serotype 3 GMTs were lower for the high-dose VPV at 18,905 (95% CI, 8737-40,906) than for cIPV at 61,431 (95% CI, 31,123-121,251), 100% of high-dose VPV recipients achieved neutralizing titers [&ge;]1:1024. CONCLUSIONS A single dose of VPV was safe and highly immunogenic, supporting its potential as a next-generation vaccine to advance global polio eradication. (Funded by the Gates Foundation and Tianjin Leading Enterprises Innovative project 23YDLQSY00100; ClinicalTrials.gov number, NCT06101173).