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Background: Respiratory syncytial virus (RSV) is a significant cause of infant morbidity and mortality worldwide. Most children experience at least one 1 RSV infection by the age of two 2 years, but not all develop severe disease. However, the understanding of genetic risk factors for severe RSV is incomplete. Consequently, we conducted a genome-wide association study of RSV severity., Methods: Disease severity was assessed by the ReSVinet scale, in a cohort of 251 infants aged 1 week to 1 year. Genotyping data were collected from multiple European study sites as part of the RESCEU Consortium. Linear regression models were used to assess the impact of genotype on RSV severity and gene expression as measured by microarray., Results: While no SNPs reached the genome-wide statistical significance threshold (P < 5 × 10-8), we identified 816 candidate SNPs with a P-value of <1 × 10-4. Functional annotation of candidate SNPs highlighted genes relevant to neutrophil trafficking and cytoskeletal functions, including LSP1 and RAB27A. Moreover, SNPs within the RAB27A locus significantly altered gene expression (false discovery rate, FDR P < .05)., Conclusions: These findings may provide insights into genetic mechanisms driving severe RSV infection, offering biologically relevant information for future investigations., Competing Interests: Potential conflicts of interest. F. M.-T. and P. J. M. O. have received honoraria from the GSK group of companies, Pfizer, Sanofi Pasteur, MSD, Seqirus, AstraZeneca, Moderna, and Janssen for taking part in advisory boards and expert meetings and for acting as a speaker in congresses outside the scope of the submitted work. F. M.-T. has also acted as principal investigator in randomized controlled trials of the aforementioned companies as well as Ablynx, Gilead, Regeneron, Roche, Abbott, Novavax, and MedImmune, with honoraria paid to his institution. S. B. D. has received honoraria from MSD and Sanofi for taking part in RSV advisory boards and has provided consultancy and/or investigator roles in relation to product development for Janssen, AstraZeneca, Pfizer, Moderna, Valneva, MSD, iLiAD, and Sanofi with fees paid to St George's, University of London. S. B. D. is a member of the UK Department of Health and Social Care's Joint Committee on Vaccination and Immunisation RSV subcommittee and Medicines and Healthcare Products Regulatory Agency's Paediatric Medicine Expert Advisory Group, but the reviews expressed herein do not necessarily represent any of those groups. A. J. P. is chair of the Department of Health and Social Care's Joint Committee on Vaccination and Immunisation. J. W. participated in the advisory board of Janssen and Sanofi with fees paid to University Medical Centre Utrecht and has been an investigator for clinical trials sponsored by pharmaceutical companies including AstraZeneca, Merck, Pfizer, Sanofi, and Janssen. All funds have been paid to University Medical Centre Utrecht. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Antibodies against Haemophilus influenzae type b (Hib) and serogroup C Neisseria meningitidis (MenC) persist better to 3½ years of age after a 12-month booster dose of a combination Hib-MenC glycoconjugate vaccine (Hib-MenC-TT) in children primed in infancy with Hib-MenC-TT and diphtheria-tetanus-acellular-pertussis-inactivated poliovirus vaccine (DTaP-IPV) than in those who received a monovalent MenC-CRM197 and DTaP-IPV-Hib (also TT conjugated). Pertussis antibodies against filamentous hemagglutinin and pertactin are higher at 5 and 12 months in children who received DTaP-IPV compared with those immunized with DTaP-IPV-Hib. We evaluated whether these differences persisted to later childhood, following a preschool booster of DTaP-IPV at 3½ years of age., Methods: Children in the United Kingdom and Poland previously enrolled in the aforementioned randomized-controlled trial had a blood sample taken at 5 years of age. Antipolyribosylribitol phosphate (Hib) IgG and MenC bactericidal antibody (baby rabbit complement) titers were compared between those immunized in infancy (at 2, 3 and 4 months) with DTaP-IPV/Hib-MenC-TT (Hib-MenC-TT group) and those who received DTaP-IPV-Hib with a monovalent MenC-CRM197 (control group). Antibody concentrations against filamentous hemagglutinin, pertactin and pertussis toxin were also measured at this visit., Results: Two hundred sixty-eight participants aged 58-64 months were enrolled. MenC baby rabbit complement titers ≥1:8 were seen in 115 of 194 of the Hib-MenC-TT group (59.3% [52.0-66.3%]) and 26 of 58 (44.8% [31.7-58.5%]) of control group participants. MenC baby rabbit complement geometric mean titers were 30.4 and 11.3, respectively (ratio 2.70 [1.55- .73]). Antipolyribosylribitol phosphate (Hib) IgG concentrations ≥ 1.0 μg/mL were seen in 171 of 197 (86.8% [81.3-91.2%]) of the Hib-MenC-TT group and 36 of 58 (62.1% [48.4-74.5%]) of control group participants. Antipolyribosylribitol phosphate IgG geometric mean concentrations (GMCs) were 3.82 and 1.67, respectively (ratio 2.29 [1.59-3.28]). Sixty-eight UK participants aged 58-63 months had sera analyzed for the pertussis antigens (44 DTaP-IPV recipients, 14 DTaP-IPV-Hib recipients). Antipertussis toxin IgG GMCs were similar for participants immunized with DTaP-IPV and DTaP-IPV-Hib: 8.2 EL.U/mL (6.1 - 10.9) compared with 7.2 EL.U/mL (3.9 - 13.4). Antifilamentous hemagglutinin IgG GMCs were higher for DTaP-IPV recipients (164.7 EL.U/mL [119.4-227.1]) compared with DTaP-IPV-Hib recipients (66.8 EL.U/mL [43.8-101.7]), as were antipertactin IgG GMCs: 102.8 EL.U/mL (67.1-157.3) compared with 23.4 EL.U/mL (15.1-36.2)., Conclusion: Vaccines used for infant immunization against Hib and MenC differ in their ability to prime responses to a booster dose of Hib-MenC-TT, and this difference persists to at least 5 years of age. Persistence of antipertussis antibody following a preschool booster of DTaP-IPV is also influenced by immunizations received at 2, 3 and 4 months of age, underlining the importance of infant immune priming in the maintenance of antibody levels through childhood.

Background: Antibodies against Haemophilus influenzae type b (Hib) and serogroup C Neisseria meningitidis (MenC) wane after early infant immunization., Methods: Children previously immunized in a randomized controlled trial at ages 2, 3, and 4 months with DTPa-IPV-Hib and MenC-CRM197 (MenC-CRM group) or DTPa-IPV and Hib-MenC-TT (Hib-MenC-TT group) had blood samples drawn at 1 and 2 years following a booster dose of Hib-MenC-TT at 12 to 15 months of age. A blood sample was also drawn at the year 2 follow-up from a separately recruited age-matched control group who had not received a booster., Results: In 271 children at year 1, mean 14.6 months (range: 12-18 months) following the Hib-MenC-TT booster, MenC bactericidal titers above the protective threshold (rSBA ≥ 1:8) was demonstrated in 89.0% of the Hib-MenC-TT group and 69.5% of MenC-CRM participants. Antipolyribosylribitol phosphate Ig ≥ 1.0 μg/mL (Hib correlate for long-term protection) was seen in 94.9% and 82.5%, respectively.In 379 participants (including 72 control children) at year 2 (age: 39-43 months, 25-31 months post Hib-MenC-TT) persistence of MenC antibodies was demonstrated in 67.1% of the Hib-MenC-TT group and 40.5% of the MenC-CRM group, compared with 44.1% of control group participants. Antipolyribosylribitol phosphate Ig ≥ 1.0 μg/mL was seen in 89.0%, 74.7%, and 38.9%, respectively., Conclusions: A toddler Hib-MenC-TT booster helps sustain immunity against Hib to 3½ years of age. Persistence of MenC antibody is similar in children primed with MenC-CRM197 in infancy who receive a booster Hib-MenC-TT, to those who receive no booster. Persistence of MenC antibody is better when primed and boosted with Hib-MenC-TT.

Glycoconjugate vaccines have dramatically reduced the incidence of encapsulated bacterial diseases in toddlers under 2 years of age, but vaccine-induced antibody levels in this age group wane rapidly. We immunized adults and 12-month-old toddlers with heptavalent pneumococcal conjugate vaccine to determine differences in B-cell and antibody responses. The adults and 12-month-old toddlers received a pneumococcal conjugate vaccine. The toddlers received a second dose at 14 months of age. The frequencies of diphtheria toxoid and serotype 4, 14, and 23F polysaccharide-specific plasma cells and memory B cells were determined by enzyme-linked immunospot assay. The toddlers had no preexisting polysaccharide-specific memory B cells or serum immunoglobulin G (IgG) antibody but had good diphtheria toxoid-specific memory responses. The frequencies of plasma cells and memory B cells increased by day 7 (P < 0.0001) in the adults and the toddlers following a single dose of conjugate, but the polysaccharide responses were significantly lower in the toddlers than in the adults (P = 0.009 to <0.001). IgM dominated the toddler antibody responses, and class switching to the IgG was serotype dependent. A second dose of vaccine enhanced the antibody and memory B-cell responses in the toddlers but not the ex vivo plasma cell responses. Two doses of pneumococcal conjugate vaccine are required in toddlers to generate memory B-cell frequencies and antibody class switching for each pneumococcal polysaccharide equivalent to that seen in adults.

Influenza is a viral infection which affects people of all ages, it is usually a self-limiting disease but it can lead to complications. This article gives an overview of influenza, looking at the disease and its possible complications. It gives a brief overview of the seasonal changes to the virus and how the World Health Organization (WHO) collects data on this and then makes recommendations on the composition of the vaccination. It outlines the vaccination itself and the current UK recommendations for influenza vaccination. Last, it focuses on paediatric influenza vaccination; the current paediatric immunisation policy and the factors that would influence a change in this policy, including reliable country-specific data on hospitalisations, the possible economic and social costs or benefits and the logistics of supplying and administering a national paediatric programme.

We conducted a phase 3 randomized controlled trial looking at the immunogenicity and safety of a novel combined Haemophilus influenzae type b and Neisseria meningitidis serogroup C tetanus toxoid conjugate vaccine, Hib-MenC-TT in a 2-, 3-, and 4-month primary infant immunization schedule. SBA MenC titers > or =1:8 and anti-PRP concentrations > or =0.15 microg/mL were measured in 99.2% and 100%, respectively, of the infants receiving Hib-MenC-TT.