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The Oxford Vaccine Group is an independent multi-disciplinary clinical trials and epidemiology group based at the Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford. OVG works towards the goal of developing new and improved vaccines for the prevention of infection in adults and children.
Heterologous COVID-19 vaccine schedule with protein-based prime (NVX-CoV2373) and mRNA boost (BNT162b2) induces strong humoral responses: results from COV-BOOST trial.
BACKGROUND: Heterologous schedules of booster vaccines for COVID-19 following initial doses of mRNA or adenoviral vector vaccines have been shown to be safe and immunogenic. There are few data on booster doses following initial doses of protein nanoparticle vaccines. METHODS: Participants of the phase 3 clinical trial of the COVID-19 vaccine NVX-CoV2373 (EudraCT 2020-004123-16) enrolled between September 28 and November 28, 2020, who received 2 doses of NVX-CoV2373 administered 21 days apart were invited to receive a third dose booster vaccine of BNT162b2 (wild type mRNA vaccine) as a sub-study of the COV-BOOST clinical trial, and were followed up for assessment of safety, reactogenicity and immunogenicity to day 242 post-booster. RESULTS: The BNT162b2 booster following two doses of NVX-COV2373 was well-tolerated. Most adverse events were mild to moderate, with no serious vaccine-related adverse events reported. Immunogenicity analysis showed a significant increase in spike IgG titres and T-cell responses post-third dose booster. Specifically, IgG levels peaked at day 14 with a geometric mean concentration (GMC) of 216,255 ELISA laboratory units (ELU)/mL (95% CI 191,083-244,743). The geometric mean fold increase from baseline to day 28 post-boost was 168.6 (95% CI 117.5-241.8). Spike IgG titres were sustained above baseline levels at day 242 with a GMC of 58,686 ELU/mL (95% CI 48,954-74,652), with significant decay between days 28 and 84 (geometric mean ratio 0.58, 95% CI 0.53-0.63). T-cell responses also demonstrated enhancement post-booster, with a geometric mean fold increase of 5.1 (95% CI 2.9-9.0) at day 14 in fresh samples and 3.0 (95% CI 1.8-4.9) in frozen samples as measured by ELISpot. In an exploratory analysis, participants who received BNT162b2 after two doses of NVX-COV2373 exhibited higher anti-spike IgG at Day 28 than those who received homologous three doses of BNT162b2, with a GMR of 5.02 (95% CI: 3.17-7.94). This trend remained consistent across all time points, indicating a similar decay rate between the two schedules. CONCLUSIONS: A BNT162b2 third dose booster dose in individuals primed with two doses of NVX-COV2373 is safe and induces strong and durable immunogenic responses, higher than seen in other comparable studies. These findings support the use and investigation of heterologous booster strategies and early investigation of heterologous vaccine technology schedules should be a priority in the development of vaccines against new pathogens.
Plasmodium falciparum Subtilisin-like Domain-Containing Protein (PfSDP), a Cross-Stage Antigen, Elicits Short-Lived Antibody Response Following Natural Infection with Plasmodium falciparum
With the increasing detection of artemisinin resistance to front-line antimalarials in Africa and notwithstanding the planned roll-out of RTS’S and R21 in Africa, the search for new vaccines with high efficacy remains an imperative. Towards this endeavour, we performed in silico screening to identify Plasmodium falciparum gametocyte stage genes that could be targets of protection or diagnosis. Through the analysis we identified a gene, Pf3D7_1105800, coding for a Plasmodium falciparum subtilisin-like domain-containing protein (PfSDP) and thus dubbed the gene Pfsdp. Genetic diversity assessment revealed the Pfsdp gene to be relatively conserved across continents with signs of directional selection. Using RT qPCR and Western blots, we observed that Pfsdp is expressed in all developmental stages of the parasite both at the transcript and protein level. Immunofluorescence assays found PfSDP protein co-localizing with PfMSP-1 and partially with Pfs48/45 at the asexual and sexual stages, respectively. Further, we demonstrated that anti-PfSDP peptide-specific antibodies inhibited erythrocyte invasion by 20–60% in a dose-dependent manner, suggesting that PfSDP protein might play a role in merozoite invasion. We also discovered that PfSDP protein is immunogenic in children from different endemic areas with antibody levels increasing from acute infection to day 7 post-treatment, followed by a gradual decay. The limited effect of antibodies on erythrocyte invasion could imply that it might be more involved in other processes in the development of the parasite.
Bivalent prefusion F vaccination in pregnancy and respiratory syncytial virus hospitalisation in infants in the UK: results of a multicentre, test-negative, case-control study.
BACKGROUND: Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory infections (ALRI) in infants younger than 6 months globally. A maternal bivalent RSV prefusion F (RSVpreF) vaccine was introduced to the UK in late summer in 2024 (August 12 in Scotland and September 1 in England), with all pregnant women at 28 weeks or more of gestation eligible for vaccination. We aimed to understand RSVpreF vaccine effectiveness in a real-world setting. METHODS: We conducted a multicentre, test-negative, case-control study to analyse the vaccine effectiveness of maternal RSVpreF vaccination against the primary outcome of hospitalisation (ie, admission to hospital) for RSV-associated ALRI in infants. Patient and public involvement from a group of parents informed the study protocol design. Included patients were infants with ALRI born after Aug 12, 2024 (Scotland), and Sept 1, 2024 (England), and therefore had mothers eligible for maternal vaccination, who were admitted to 30 hospital sites across the UK from Sept 30, 2024, to Jan 20, 2025, and tested for RSV. Infants were followed up until hospital discharge or death as an inpatient. Primary vaccine effectiveness of maternal RSVpreF vaccination against RSV-associated hospitalisation was calculated with the use of a conditional logistic regression adjusted by site, calendar month of hospital attendance for the infant, age, preterm birth, and sex. FINDINGS: We included 537 mother-infant pairs, in whom there were 391 RSV-positive infant cases (median age 1·63 months [IQR 0·94-2·26]) and 146 RSV-negative infant controls (1·41 months [0·77-2·03]). Of 537 recruited infants, 297 (55%) were male and 240 (45%) were female. Ethnicity data were available for 533 mothers, of whom 434 (81%) self-identified as White. The mothers of 73 (19%) RSV-positive cases and 60 (41%) RSV-negative controls had received RSVpreF vaccine before delivery. The adjusted effectiveness of maternal RSVpreF vaccination for preventing infant hospitalisation was 58% (95% CI 28-75) for infants whose mothers were vaccinated at any time before delivery and 72% (48-85) for infants whose mothers were vaccinated more than 14 days before delivery (39 [11%] of 357 RSV-positive cases vs 43 [33%] of 129 RSV-negative controls). INTERPRETATION: In the real-world setting of the first season of vaccine implementation in England and Scotland, maternal RSVpreF vaccination was effective and equivalent to trial settings in reducing the risk of hospitalisation in infants with RSV-associated ALRI. FUNDING: National Institute for Health and Care Research, The Wellcome Trust, and Imperial College London.
Salmonella Typhi gut invasion drives hypoxic immune subsets associated with disease outcomes
Salmonella Typhi (S. Typhi), the causative agent of typhoid disease, remains a major public health concern. Owing to the human-restricted nature of S. Typhi, studies of typhoid pathogenesis in animal models are limited to a murine non-typhoidal pathogen. More recently, human challenge models have been conducted, providing insight into immune correlates of infection outcomes, which are still incompletely understood. Here, we performed an integrated single-cell analysis of immune responses from the human S. Typhi challenge model and mouse model of typhoid disease, to associate biological mechanism with human infection outcome. Most prominent, we revealed immune subsets with a hypoxia-related signature in the blood of individuals who developed disease in the human challenge model. This signature was also evident in the mouse model in activated macrophages infiltrating into the Peyer’s patches, but not during infection with a mutant strain impaired for gut invasion. We further identified hypoxia-related signature as a general immune correlate of disease outcome in other infection-and inflammatory-related diseases. Collectively, we identified a hypoxia-associated immune signature that correlates with disease outcomes in humans. Using a mouse model, we demonstrated that this signature is driven by bacterial invasion to the Peyer’s patches, implicating a causal role in the pathogenesis of typhoid fever.
Nipah virus vaccines evaluated in pigs as a 'One Health' approach to protect public health.
Nipah virus (NiV) causes a severe neurological disease in humans. The first NiV outbreak, in Malaysia, involved pig-to-human transmission, that resulted in significant economic losses to the local pig industry. Despite the risk NiV poses to pig-dense regions, no licensed vaccines exist. This study therefore assessed three NiV vaccine candidates in pigs: (1) adjuvanted soluble NiV (s)G protein, (2) adjuvanted pre-fusion stabilised NiV (mcs)F protein, and (3) adenoviral vectored NiV G (ChAdOx1 NiV G). NiV sG induced the strongest neutralising antibody response, NiV mcsF induced antibodies best able to neutralise cell-cell fusion, whereas ChAdOx1 NiV G elicited CD8+ T-cell responses. Despite differences in immunogenicity, prime-boost immunisation with all candidates conferred a high degree of protection against NiV infection. Follow-up studies demonstrated longevity of immune responses and broadly comparable immune responses in Bangladeshi pigs under field conditions. These studies provide a platform for developing a NiV vaccine for pigs.
Understanding the interaction of upper respiratory tract infection with respiratory syncytial virus and Streptococcus pneumoniae using a human challenge model: a multicenter, randomized controlled study protocol.
BACKGROUND: Streptococcus pneumoniae (pneumococcus) and respiratory syncytial virus (RSV) are major causes of respiratory infections globally. Viral and bacterial co-infections are commonly observed in respiratory infections and there is evidence that these pathogens interact synergistically to evade host responses and lead to more severe disease. Notably, RSV seasonal outbreaks are associated with increased hospitalization and a subsequent peak in invasive pneumococcal disease cases, particularly in pediatric populations. Here, we summarize a protocol for a controlled human infection model aiming to evaluate pathogen interaction dynamics and immune responses in a combined pneumococcus and RSV model. The primary objective is to determine whether primary RSV challenge increases the risk of secondary pneumococcal colonization. METHODS: This is an open-label, multi-center, randomized controlled human co-infection study, inclusive of a pilot phase. Individuals will be randomized to primary inoculation with either pneumococcus (serotype 6B) or RSV (subtype RSV-A) intra-nasally on day 0 followed by a reciprocal challenge on day 7. During pilot phase A up to 10 participants will be monitored in an in-patient facility for 7-10 days following RSV-A challenge. If there are no safety concerns, we will then progress to an outpatient phase where participants will self-isolate at home. Clinical samples to be taken from participants include nasal swabs and washes for pathogen detection; and nasal cells, nasal lining fluid, and blood samples to examine mucosal and systemic immune responses. DISCUSSION: This work will lead to important scientific knowledge on the interaction and dynamics between pneumococcus and RSV. This knowledge could help inform pneumococcal and RSV vaccination strategies, particularly for groups at risk of developing severe pneumococcal and RSV disease. TRIAL REGISTRATION: The study is registered on ISRCTN (The UKs Clinical Study Registry). DOI https://doi.org/10.1186/ISRCTN12036902.
Defining the genetic determinants of CD8+ T cell receptor repertoire in the context of immune checkpoint blockade.
The relationship between genetic variation and CD8+ T cell receptor (TCR) repertoire usage in patients receiving immune checkpoint blockade (ICB) therapy for cancer is unexplored. We have conducted a genome-wide and human leukocyte antigen (HLA)-focused analysis of CD8+ TCR repertoire to identify genetic determinants of variable gene (V-gene) and CDR3 K-nucleotide oligomer usage from samples taken before and after ICB (n = 250). We identify 11 cis and 10 trans V-gene associations, primarily to the MHC, that meet genome-wide significance. TCR clones containing HLA associated V-genes were less stable across treatment, while, at the single-cell level, genetically associated clones demonstrate subset enrichment and increased tumor reactivity expression profiles. Notably, patients with HLA-matched TCR clones demonstrate improved overall survival. Our work indicates a complex relationship between genotype and TCR repertoire in the context of ICB treatment, with implications for understanding factors relating to therapeutic response and patient outcomes.
Neonatal Antifungal Consumption Is Dominated by Prophylactic Use; Outcomes From The Pediatric Antifungal Stewardship: Optimizing Antifungal Prescription Study.
BACKGROUND: Diagnostic challenges combined with the vulnerability of neonates to develop invasive candidiasis (IC) may lead to antifungal administration in the absence of IC. A modified point-prevalence study was performed to obtain an improved insight and understanding of antifungal prescribing in this specific patient population. METHODS: Neonates and infants ≤90 days of age receiving systemic antifungals from 12 centers in England were included. Data were collected prospectively during 26 consecutive weeks and entered into an online REDCap database. RESULTS: Two hundred eighty neonates and infants were included, the majority ≤1 month of age (68.2%). Prematurity was the commonest underlying condition (68.9%). Antifungals were prescribed for prophylactic reason in 79.6%; of those, 64.6% and 76.3% were extreme low birth weight infants and prematurely born neonates, respectively. Additional risk factors were present in almost all patients, but only 44.7% had ≥3 risk factors rendering them more susceptible to develop IC. Nonpremature and non extremely low birth weight premature infants only scored ≥3 risk factors in 32.6% and 15%, respectively. Fluconazole was the most common antifungal used (76.7% of all prescriptions), and commonly underdosed as treatment. The number of microbiologic proven IC was low, 5.4%. CONCLUSIONS: Neonatal antifungal prophylaxis is commonly prescribed outside the recommendations based on known risk profiles. Fluconazole is the main antifungal prescribed in neonates and infants, with underdosing frequently observed when prescribed for treatment. Number of proven IC was very low. These observations should be taken into consideration to develop a national pediatric Antifungal Stewardship program aiming to guide rational prescribing.
Case Report: Disseminated, rifampicin resistant Mycobacterium bovis (BCG) infection in an immunocompromised child
<ns4:p><ns4:bold>Background: </ns4:bold><ns4:italic>Bacillus Calmette–Guérin</ns4:italic> (BCG) is a live-attenuated vaccine used world-wide for prevention of tuberculosis disease. In some immunocompromised hosts it has the potential to cause disease. As with other members of the <ns4:italic>M. tuberculosis </ns4:italic>complex it has the potential for acquiring drug resistance.</ns4:p><ns4:p> <ns4:bold>Methods: </ns4:bold>We reviewed 10 years of paediatric clinical BCG strains referred to our clinical microbiology laboratory in Oxford where they underwent whole genome sequencing. We present a case series comparing clinical, pathogen genetic and pathogen phenotypic data, and consider the clinical implications.</ns4:p><ns4:p> <ns4:bold>Results: </ns4:bold>We identified 15 BCG isolates from 8 children under 16 years old. Only one child had clinical disease with the other seven reported as local inoculation-site reactions. Case 1 suffered disseminated disease secondary to an undiagnosed IL-12/IFNγ receptor defect and the BCG isolates evolved two different rifampicin resistance mutations. Across all 15 isolates, phenotypic resistance to each first line drug was seen. </ns4:p><ns4:p> <ns4:bold>Conclusions: </ns4:bold>BCG is a safe and effective vaccine in children. Most clinical specimens in our series were not related to disease. However, in the context of rare pathogen-specific immunocompromise, BCG can cause pathology and acquire drug resistance under selection from therapy.</ns4:p>
Simultaneous Viral Whole-Genome Sequencing and Differential Expression Profiling in Respiratory Syncytial Virus Infection of Infants.
Targeted metagenomics using strand-specific libraries with target enrichment is a sensitive, generalized approach to pathogen sequencing and transcriptome profiling. Using this method, we recovered 13 (76%) complete human respiratory syncytial virus (RSV) genomes from 17 clinical respiratory samples, reconstructed the phylogeny of the infecting viruses, and detected differential gene expression between two RSV subgroups, specifically, a lower expression of the P gene and a higher expression of the M2 gene in RSV-A than in RSV-B. This methodology can help to relate viral genetics to clinical phenotype and facilitate ongoing population-level RSV surveillance and vaccine development.
Real-world uptake of nirsevimab, RSV maternal vaccine, and RSV vaccines for older adults: a systematic review and meta-analysis.
BACKGROUND: In clinical trials, recently introduced respiratory syncytial virus (RSV) immunisation products have shown high efficacy in preventing severe RSV outcomes. Implementing successful immunisation programmes is however key to realising these benefits in real-world settings. We aimed to investigate uptake of the long-acting monoclonal antibody nirsevimab, the RSV maternal vaccine, and RSV vaccines for older adults in countries where immunisation programmes have been introduced, and to explore how uptake varies between countries and population subgroups. METHODS: In this systematic review and meta-analysis, we carried out four monthly searches in Medline, Embase, and Global Health databases for studies reporting uptake of nirsevimab, the RSV maternal vaccine, and RSV vaccines for older adults. We included population-based studies published between December 1, 2022 and February 5, 2025. Two independent reviewers screened studies, extracted data, and completed a risk of bias assessment using the Joanna Briggs Institute (JBI) Critical Appraisal Tools. We assessed uptake stratified by country and socio-demographic and clinical subgroups. Meta-analyses were conducted using random-effects modelling. PROSPERO registration number: CRD42025643585. FINDINGS: We screened a total of 1267 studies, 43 of which met the inclusion criteria reporting data on over 1.38 million individuals from six countries. Nirsevimab uptake data were reported in 34 studies: 16 from Spain, eight from the United States, seven from France, one with combined data from Andorra and Spain, and one from each of Italy and Luxembourg. Our pooled estimates showed that nirsevimab uptake on population level was 90.1% (95% confidence interval (CI): 86.4-92.9) in Spain and 51.2% (95% CI: 29.3-72.7) in the United States during the 2023/24 RSV season. Uptake data for the RSV maternal vaccine and RSV vaccines for older adults were reported in five and eight studies, respectively, all from the United States. Meta-analysis showed population-level uptake of 30.5% (95% CI: 20.6-42.6) and 18.2% (95% CI: 10.8-28.9), respectively. Uptake varied across subgroups. INTERPRETATION: Uptake of nirsevimab varied substantially between the countries that have implemented infant RSV immunisation programmes. Despite the limited number of studies and the lack of more accurate data at national level the low uptake estimates for RSV maternal vaccine and RSV vaccines for older adults are concerning. National, clinical, and public health initiatives are needed to increase uptake of RSV immunisation products and ensure maximum benefit to people currently at risk of severe RSV outcomes. FUNDING: Health Data Research UK, Inflammation and Immunity Driver Programme.