Background: Reduced-dosing pneumococcal conjugate vaccine (PCV) schedules (single-primary plus booster; 1+1) are being considered and deployed in some countries. We evaluated persistence of serotype-specific immunity through five years of age in infants randomised to 1+1 or two-dose primary plus booster (2+1) schedules of 10-valent (PCV10; GSK) or 13-valent (PCV13; Pfizer) vaccine. Methods: In an open-label, randomised, non-inferiority trial, HIV-unexposed infants were randomised into six groups: single-dose PCV10 or PCV13 at 6 weeks (6w+1) or 14 weeks (14w+1), or two doses at 6 and 14 weeks (2+1), all receiving a booster at 9 months. Serotype-specific serum IgG geometric mean concentrations (GMCs) were measured by in-house Luminex assay at three, four, and five years of age. Non-inferiority was defined as the lower bound of the 95% confidence interval of the GMC ratio exceeding 0.5 for ≥10 of 13 PCV13 serotypes and ≥8 of 10 PCV10 serotypes. The trial is registered at ClinicalTrials.gov (NCT04275284). Findings: 986 blood samples were collected across three annual visits (349, 334, and 303 at three, four, and five years, respectively) between 18 February 2020 and 24 August 2022. Both PCV13 1+1 schedules remained non-inferior to the 2+1 schedule through five years. Both PCV10 1+1 schedules met non-inferiority at three years but failed criteria at four and five years. Direct comparison of the two 2+1 schedules demonstrated higher GMCs in the PCV13 group for all common serotypes at all timepoints, except serotype 9V at four and five years. Interpretation: A reduced PCV13 1+1 schedule, with priming at either 6 or 14 weeks, maintained non-inferior serotype-specific IgG GMCs relative to the 2+1 schedule through five years of age, supporting schedule transition in countries with well-established PCV programmes. This was not demonstrated for PCV10.

Background/Objectives: Generalised immune dysfunction in chronic kidney disease, especially in patients requiring haemodialysis (HD), significantly enhances the risk of severe infections. Vaccine-induced immunity is typically reduced in HD populations. The SARS-CoV-2 pandemic provided an opportunity to examine the magnitude and functionality of antibody responses in HD patients to a previously unencountered antigen—Spike (S)-glycoprotein—after vaccination with different vaccine platforms (viral vector (VV); mRNA (mRV)). Methods: We compared the total and functional anti-S antibody responses (cross-variant neutralisation and complement binding) in 187 HD patients and 43 healthy controls 21–28 days after serial immunisation. Results: After 2 doses of the same vaccine, HD patients had anti-S antibody levels and a complement binding capacity comparable to controls. However, 2 doses of mRV induced greater polyfunctional antibody responses than VV (defined by the presence of both complement binding and cross-variant neutralisation activity). Interestingly, an mRV boost after 2 doses of VV significantly enhanced antibody functionality in HD patients without a prior history of SARS-CoV-2 infection. Conclusions: HD patients can generate near-normal, functional antigen-specific antibody responses following serial vaccination to a novel antigen. Encouragingly, exploiting immunological memory by using mRNA vaccines and boosting may improve the success of vaccination strategies in this vulnerable patient population.

BACKGROUND:While coronavirus disease 2019 (COVID-19) is primarily a respiratory infection, few studies have characterised the immune response to COVID-19 in lung tissue. We sought to understand the pathogenic role of microenvironmental interactions and the extracellular matrix in post-mortem COVID-19 lung using an integrative multi-omic approach. METHODS:Post-mortem formalin-fixed paraffin-embedded lung tissue from fatal COVID-19 and nonrespiratory death control lung underwent multi-omic evaluation by Quantseq Bulk RNA sequencing, Nanostring GeoMx spatial transcriptomics, RNAscope, multiplex immunofluorescence and immunohistochemistry, to evaluate virus distribution, immune composition and the extracellular matrix. Markers of extracellular synthesis and breakdown were measured in the serum of 215 patients with COVID-19 and 54 healthy volunteer controls using ELISA. RESULTS:We found that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was restricted to the pneumocytes and macrophages of early-stage disease. Spatial analyses revealed an immunosuppressive virus microenvironment, enriched for PDL1+IDO1+ macrophages and depleted of T-cells. Oligoclonal T-cells in COVID-19 lung showed no enrichment of SARS-CoV-2 specific T-cell receptors. Collagen VI was upregulated and contributed to alveolar wall thickening and impaired gas exchange in COVID-19 lung. Serum from COVID-19 patients showed increased levels of PRO-C6, a marker of collagen VI synthesis, predicted mortality in hospitalised patients. CONCLUSIONS:Our data refine the current model of respiratory COVID-19 with regard to virus distribution, immune niches and the role of the noncellular microenvironment in pathogenesis and risk stratification in COVID-19. We show that collagen deposition is an early event in the course of the disease.

Background & Aims: Effective control of chronic liver diseases (CLD) requires suppression of effector T cells by CD4+CD25+CD127low regulatory T cells (Tregs). This study investigated the role of TIGIT, a co-inhibitory receptor, in CLD by examining the phenotype, recruitment, localisation, and function of TIGIT+Tregs and how TIGIT augments Treg function. We also elucidated the function of TIGIT+effector T cells on hepatocytes. Methods: Liver infiltrating (CLD explants n = 7, donor liver n = 4) and peripheral (CLD blood n = 22, healthy control blood n = 10) TIGIT+Tregs and TIGIT+effector T cells were phenotyped by flow cytometry, and their localisation was examined by immunohistochemistry. Phenotypic and functional changes in TIGIT+Tregs in response to TIGIT agonism and IL-2 supplementation were also assessed. TIGIT+effector T cell-induced primary hepatocyte apoptosis was investigated using co-culture experiments and blocking assays. Results: TIGIT+Tregs were more suppressive towards CD4+T cells than TIGIT-Tregs (p = 0.04254), and their suppressive action was IL-10 dependent. TIGIT expression was highly enriched on intrahepatic Tregs compared to effector T cells (p <0.0001). TIGIT+Tregs and TIGIT+effector T cells expressed CXCR3 and VLA-4 and localised around hepatocytes which express TIGIT ligand, CD155. TIGIT+Tregs also exhibited significantly higher cytotoxic T lymphocyte-associated antigen-4 (CTLA-4; p = 0.0012), FoxP3 (p <0.0001), and CD39 (p <0.0001) expression than TIGIT-Tregs. TIGIT agonism upregulated FoxP3 and CTLA-4 on Tregs, reduced proliferation, and increased TNF-α expression. Supplementing TIGIT+Tregs with IL-2 further enhanced FoxP3 and CTLA-4 expression. In contrast, TIGIT+effector T cells displayed reduced cytotoxicity towards hepatocytes, which reversed upon TIGIT blockade. Conclusions: TIGIT+Tregs are highly suppressive and can be enhanced in response to TIGIT agonism and IL-2 stimulation, demonstrating their translational therapeutic potential. However, TIGIT blockade on CD8+T cells induces hepatitis, caution is required when using anti-TIGIT therapy. Impact and implications: We identified a highly suppressive subset of regulatory T cells in the liver, defined as TIGIT+CD39+CTLA-4+Tregs. TIGIT agonists and IL-2 enhanced the suppressive function of this cell subset. The TIGIT ligand, CD155, is expressed on inflamed hepatocytes, and TIGIT blockade in oncology could instigate checkpoint inhibitor induced liver injury (CHILI). These findings have implications for future therapy in liver disease.

Vaccines are less immunogenic in older adults, partly due to immunosenescence. Having previously shown that morning influenza vaccination may be more immunogenic in older adults (mean age 71), we assessed if this could be replicated in a younger cohort (mean age 57) and with a T-cell independent vaccine. This study examined whether diurnal timing of a single dose of Pneumovax (R) (PPV-23) and seasonal influenza vaccine influenced antibody responses in 140 healthy adults over the age of 50. Pneumococcal serotype-specific (PnPS) antibodies and Haemagglutination Inhibition Assays (HAI) were used to characterize antibody responses at Baseline, 1, 4, and 52 weeks post-vaccination. Protective thresholds were set at 0.35 mu g/mL for two-thirds of PnPS tested (WHO >= 8/12PnPS) and a titre of >= 40 HAI for H1N1, H3N2, and B/Victoria strains. Both AM and PM cohorts showed increased Pn-specific antibodies to one PPV-23 dose at weeks 1, 4, and 52; however, time of day did not significantly influence antibody responses. Baseline immunity for pneumococcus was high (57.1 % AM, 50.0 % PM had WHO >= 8/12PnPS), and immunity was maintained with at least 7/12 serotypes elevated at 52 weeks. Time of day did not alter short- or long-term influenza antibody responses. H1N1 had the highest baseline immunity (67.6 % AM, 48.6 % PM had >= 40 HAI) and the most increased responses at week 4 post-vaccination (92.8 % AM, 94.1 % PM) that were maintained at 52 weeks post-vaccination (91.7 % AM, 89.3 % PM). The poorest serotype immunity was for the B/Victoria strain at all time points. Although time of day did not influence vaccine immunogenicity in AM and PM cohorts, sustained cohort-wide antibody responses were demonstrated in an older population. Identifying 18 % of the total cohort exhibited suboptimal responses to pneumococcal or influenza vaccines underscores the imperative for enhancing vaccine efficacy within this age group to reduce morbidity and mortality.

AIM:The EarLy Surveillance for Autoimmune (ELSA) study aims to explore the feasibility and acceptability of UK paediatric general population screening for type 1 diabetes. METHODS:We aim to screen 20,000 children aged 3-13 years for islet-specific autoantibodies through dried blood spot sample collection at home, hospital or community settings. Children with two or more autoantibodies are offered metabolic staging via oral glucose challenge testing. Feasibility assessments will compare recruitment modalities and uptake according to demographic factors (age, gender, ethnicity, level of deprivation and family history of diabetes) to determine optimal approaches for general population screening. The study is powered to identify 60 children (0.3%) with type 1 diabetes (stage 1-3). Parents are invited to qualitative interviews following ELSA completion (child screened negative or positive, single autoantibody or multiple, stage 1-3) to share their screening experience, strengths of the programme and any areas for improvement (acceptability assessments). Parents who decline screening or withdraw from participation are invited to interview to explore any concerns. Finally, we will interview professional stakeholders delivering the ELSA study to explore barriers and facilitators to implementation. CONCLUSION:Early detection of type 1 diabetes allows insulin treatment to be started sooner, avoids diagnosis as an emergency, gives families time to prepare and the opportunity to benefit from future prevention trials and treatments. ELSA will provide essential feasibility and acceptability assessments for UK general population screening to inform a future national screening programme for paediatric type 1 diabetes.

Diseases caused by SARS-CoV-2 and Mycobacterium tuberculosis (M.tb) represent two public health emergencies. In severe disease, both pathogens may share a biological niche in the lower respiratory tract. There is significant potential for SARS-CoV-2 and M.tb infections to be co-present within individuals and enhance or moderate the respective outcomes of either infection. Here, we investigated how whole blood samples, as well as CD4+ and CD8+ T cells, from individuals hospitalised with acute COVID-19 disease respond to mycobacterial challenge. To do this, samples were assessed by ex vivo mycobacterial growth inhibition assays, immune cell phenotyping by mass cytometry, and whole blood cytokine responses to mycobacterial antigens assessed by flow cytometry. These studies identified a subgroup of COVID-19 patients whose blood had an enhanced capacity to inhibit mycobacterial growth. The ability to control mycobacterial growth was associated with the presence of a non M.tb-specific CD28+ CD8+ T cell population, with a particular activation status and migratory phenotype. This work improves our understanding of factors involved in mycobacterial control, and may contribute to the design of novel therapies for TB. ### Competing Interest Statement The authors have declared no competing interest.

Objectives Vitamin D has a role in the innate immunity against pathogens and is also involved in mechanisms for reducing inflammation. VD deficiency (VDD) may increase COVID-19 infection susceptibility, however research is limited on the association between VDD and COVID-19 symptom prevalence and duration. The study aimed to determine whether VDD is a risk factor for the presence and extended duration of COVID-19 symptoms. Methods Data was analyzed from NHS healthcare workers who isolated due to COVID-19 symptoms as a part of the COVID-19 convalescent immunity study between 12th to 22nd May 2020. Participants self-reported the presence and duration of viral symptoms. Anti-SARS-CoV-2 antibodies and vitamin D (25(OH)D3) serum levels were measured on day of recruitment. VDD was defined as 25(OH)D3 levels of < 30 nmol/l. Results Of the 392 participants, 15.6% (n = 61) had VDD. VDD participants had more symptoms overall (p = 0.0030), including body aches (p = 0.0453), and extended duration of body aches (p = 0.0075) and fatigue (p = 0.0127). Binary logistic regression found that both VDD (OR 3.069, 95% CI 1.538-6.124; p = 0.001) and age (OR 1.026, 95% CI 1.003-1.049; p = 0.025) were independently associated with extended durations of body aches. VDD (OR 2.089, 95% CI 1.087-4.011; p = 0.027), age (OR 1.036, 95% CI 1.016-1.057; p < 0.001) and seroconversion (OR 1.917, 95% CI 1.203-3.056; p = 0.006), were independently associated with extended durations of fatigue. Conclusion VDD is a significant independent risk factor for extended durations of body aches and fatigue in healthcare workers who isolated for COVID-19 viral symptoms. Vitamin D supplementation may reduce symptom duration and is thus an area for future research.

Background: Immunization is recommended internationally to protect against pneumococcal infections in HIV-infected adults. However, vaccination schedule designs are mostly based on studies of initial rather than long-term antibody responses. This UK observational study investigated the short- and long-term antibody responses to polysaccharide and glycoconjugate pneumococcal vaccines in an adult HIV-infected cohort. Methods: We studied a subgroup of 152 of 839 participants from the AIR (Assessment of Immune Responses to Routine Immunisations in HIV-infected Adults, ISRCTN95588307) study, that had received pneumococcal vaccinations, and had blood samples collected pre- and post-vaccination, as well as at least annually for four subsequent calendar years. Patients received either Pneumovax-23 (PPV, N=89) or Prevenar-13 (PCV, N=63) as their primary vaccine, with immunity assessed by measuring IgG antibody concentrations for 12 pneumococcal polysaccharide serotypes (PnPS). The primary outcome was achieving IgG antibody concentrations above the recommended World Health Organisation (WHO) threshold of 0.35 mu g/ml for at least 8/12 of the PnPS assessed (WHO >= 8/12PnPS). Patients who did not achieve WHO >= 8/12PnPS after the primary vaccination were offered further vaccination with PCV; booster vaccinations with PCV were additionally offered to those where antibody levels subsequently fell below the WHO >= 8/12PnPS threshold. Results: Patients receiving PCV as their primary pneumococcal vaccine were significantly more likely to achieve WHO >= 8/12PnPS after a single vaccine dose than those receiving PPV (54% vs. 33%, p=0.012). This difference persisted following booster vaccination with PCV, with cumulative rates of WHO >= 8/12PnPS in those receiving PCV vs. PPV as the primary vaccine of 88% vs. 67% and 100% vs. 85% after receiving up to one and two booster vaccinations, respectively. Where WHO >= 8/12PnPS was achieved, this persisted significantly longer in those receiving PCV as their primary vaccine compared to PPV (median: 23.5 vs. 11.1 months; p=0.010). Conclusions: Immunization with PCV resulted in quantitatively greater antibody responses than immunization with PPV in a cohort of HIV-infected UK adults. Individuals receiving PCV as their primary vaccine required fewer total pneumococcal vaccine doses to achieve WHO >= 8/12PnPS and experienced greater duration of time above this threshold than those with PPV as the primary vaccine. However, the median longevity of both vaccine responses was relatively short, which supports the use of ongoing booster doses using high valency glycoconjugate vaccines to sustain WHO >= 8/12PnPS threshold antibody levels. (c) 2024 The Author(s). Published by Elsevier Ltd on behalf of The British Infection Association. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Generalised immune dysfunction in chronic kidney disease, especially in patients requiring haemodialysis (HD), significantly enhances the risk of severe infections. Moreover, vaccine-induced immunity is typically reduced in HD populations, but the full mechanisms behind this remain unclear. The SARS-CoV-2 pandemic provided an opportunity to examine the magnitude and functionality of antibody responses in HD patients to a previously unencountered antigen, Spike (S)-glycoprotein, after vaccination with different vaccine platforms (viral vector (VV); mRNA (mRV)). Here, we compared total and functional anti-S antibody responses (cross-variant neutralisation and complement binding) in 187 HD patients and 43 healthy controls 21-28 days after serial immunisation. After 2 doses of the same vaccine, HD patients had anti-S antibody levels and complement binding capacity comparable to controls. However, 2 doses of mRV induced greater polyfunctional antibody responses than VV, yet previous SARS-CoV-2 infection or an mRV boost after 2 doses of VV significantly enhanced antibody functionality in HD patients. Therefore, HD patients can generate near-normal, functional antigen-specific antibody responses following serial vaccination to a novel antigen, suggesting largely intact B cell memory. Encouragingly, exploiting immunological memory by using mRNA vaccines and boosting may improve the success of vaccination strategies in this vulnerable patient population.### Competing Interest StatementThe authors have declared no competing interest.

Vaccine development targeting SARS-CoV-2 in 2020 was of critical importance in reducing COVID-19 severity and mortality. In the U.K. during the initial roll-out most individuals either received two doses of Pfizer COVID-19 vaccine (BNT162b2) or the adenovirus-based vaccine from Oxford/AstraZeneca (ChAdOx1-nCoV-19). There are conflicting data as to the impact of age, sex and body habitus on cellular and humoral responses to vaccination, and most studies in this area have focused on determinants of mRNA vaccine immunogenicity. Here, we studied a cohort of participants in a population-based longitudinal study (COVIDENCE UK) to determine the influence of age, sex, body mass index (BMI) and pre-vaccination anti-Spike (anti-S) antibody status on vaccine-induced humoral and cellular immune responses to two doses of BNT162b2 or ChAdOx-n-CoV-19 vaccination. Younger age and pre-vaccination anti-S seropositivity were both associated with stronger antibody responses to vaccination. BNT162b2 generated higher neutralising and anti-S antibody titres to vaccination than ChAdOx1-nCoV-19, but cellular responses to the two vaccines were no different. Irrespective of vaccine type, increasing age was also associated with decreased frequency of cytokine double-positive CD4+T cells. Increasing BMI was associated with reduced frequency of SARS-CoV-2-specific TNF+CD8% T cells for both vaccines. Together, our findings demonstrate that increasing age and BMI are associated with attenuated cellular and humoral responses to SARS-CoV-2 vaccination. Whilst both vaccines induced T cell responses, BNT162b2 induced significantly elevated humoral immune response as compared to ChAdOx-n-CoV-19.

Background: The association between air quality and risk of SARS-CoV-2 infection is poorly understood. We investigated this association using serological individual-level data adjusting for a wide range of confounders, in a large population-based cohort (COVIDENCE UK). Methods: We assessed the associations between long-term (2015-19) nitrogen dioxide (NO2) and fine particulate matter with an aerodynamic diameter of <= 2.5 mu m (PM2.5), exposures with SARS-CoV-2 infection, level of antibody response among those infected, and COVID-19 disease severity. We used serological data from 10,489 participants in the COVIDENCE UK cohort, and estimated annual average air pollution exposure at each participant's home postcode. Results: After controlling for potential confounders, we found a positive association between 5-year NO2 and PM2.5 exposures and the risk of seropositivity: 10 unit increase in NO2 (mu g/m3) was associated with an increasing risk of seropositivity by 1.092 (95% CI 1.02 to 1.17; p-for-trend 0.012). For PM2.5, 10 unit increase (mu g/m3) was associated with an increasing risk of seropositivity by 1.65 (95% CI 1.015-2.68; p-for-trend 0.049). In addition, we found that NO2 was positively associated with higher antibody titres (p-for-trend 0.013) among seropositive participants, with no evidence of an association for PM2.5. Conclusion: Our findings suggest that the long-term burden of air pollution increased the risks of SARS-CoV-2 infection and has important implications for future pandemic preparedness. This evidence strengthens the case for reducing long-term air pollution exposures to reduce the vulnerability of individuals to respiratory viruses.

Multiple myeloma (MM) and anti-MM therapy cause profound immunosuppression, leaving patients vulnerable to coronavirus disease 2019 (COVID-19) and other infections. We investigated anti-severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibodies longitudinally in ultra-high-risk patients with MM receiving risk-adapted, intensive anti-CD38 combined therapy in the Myeloma UK (MUK) nine trial. Despite continuous intensive therapy, seroconversion was achieved in all patients, but required a greater number of vaccinations compared to healthy individuals, highlighting the importance of booster vaccinations in this population. Reassuringly, high antibody cross-reactivity was found with current variants of concern, prior to Omicron subvariant adapted boostering. Multiple booster vaccine doses can provide effective protection from COVID-19, even with intensive anti-CD38 therapy for high-risk MM.