Tessa M. John

Immunogenicity of a tetravalent meningococcal glycoconjugate vaccine in infants: a randomized controlled trial.

CONTEXT Immunization with a meningococcal tetravalent (serogroup ACWY) glycoconjugate vaccine is recommended for all US adolescents. However, the currently licensed vaccine is poorly immunogenic in infancy, when the highest rates of disease are observed. OBJECTIVE To determine the immunogenicity of a novel tetravalent CRM(197)-conjugated meningococcal vaccine (MenACWY) in infants. DESIGN, SETTING, AND PARTICIPANTS Randomized, open-label, controlled study of 225 UK and 196 Canadian 2-month-olds from August 2004 to September 2006. INTERVENTION UK infants received a primary course of MenACWY (at 2, 3, and 4 months or 2 and 4 months) or Neisseria meningitidis serogroup C monovalent meningococcal glycoconjugate vaccine (MenC) (at 2 and 4 months). All received MenACWY at 12 months. Canadian infants received MenACWY at 2, 4, and 6 months or 2 and 4 months; at 12 months they received MenACWY, a plain tetravalent polysaccharide vaccine, or no vaccine. MAIN OUTCOME MEASURE Percentage of infants with a human complement serum bactericidal activity (hSBA) titer >or=1:4 after a primary course of MenACWY and after a 12-month booster. Safety and reactogenicity of MenACWY were also assessed. RESULTS According to the prespecified per-protocol analysis, the percentages (95% CIs) of MenACWY 2-, 3-, and 4-month recipients with hSBA titers >or=1:4 after primary immunization were serogroup A, 93% (84%-98%); C, 96% (89%-99%); W-135, 97% (90%-100%); and Y, 94% (86%-98%). With a post hoc intention-to-treat analysis with imputed values for missing data, these values were unchanged for serogroups C and Y; for serogroup A, values were 92% (84%-97%), and for W-135, 97% (91%-99%). For the per-protocol analysis of MenACWY 2-, 4-, and 6-month recipients, the percentages (95% CIs) of responders were A, 81% (71%-89%); C, 98% (92%-100%); W-135, 99% (93%-100%); and Y, 98% (92%-100%). With the imputed value analysis, these values were A, 83% (74%-89%); C, 98% (93%-99%); W-135, 99% (94%-100%); and Y, 98% (92%-99%). At least 84% of MenACWY 2- and 4-month recipients achieved hSBA titers >or=1:4 for serogroups C, W-135, and Y after primary immunization, as did at least 60% for serogroup A (per-protocol and imputation analysis). At least 95% of primary and booster MenACWY recipients achieved hSBA titers >or=1:4 for serogroups C, W-135, and Y at 13 months, as did at least 84% for serogroup A (per-protocol and imputation analysis). During the primary immunization course, postimmunization pain on leg movement was observed in 2% of UK MenACWY 2- and 4-month recipients and 4% of MenC 2- and 4-month recipients; a temperature of 38 degrees C or greater was observed in 4% and 2% in these groups, respectively. CONCLUSION MenACWY is well tolerated and immunogenic in infancy. Trial Registration clinicaltrials.gov Identifier: NCT00262002.

Multicenter, Open-Label, Randomized Phase II Controlled Trial of an Investigational Recombinant Meningococcal Serogroup B Vaccine With and Without Outer Membrane Vesicles, Administered in Infancy

BACKGROUND In the absence of an efficacious broadly protective vaccine, serogroup B Neisseria meningitidis (MenB) is the leading cause of bacterial meningitis and septicemia in many industrialized countries. An investigational recombinant vaccine that contains 3 central proteins; Neisserial adhesin A (NadA), factor H binding protein (fHBP) and Neisserial heparin binding antigen (NHBA) has been developed. These antigens have been formulated with and without outer membrane vesicles (rMenB+OMV and rMenB, respectively) from the New Zealand epidemic strain (B:4:P1.7-2,4). In this trial, we assessed the immunogenicity of these formulations in infants, who are at greatest risk of contracting MenB disease. METHODS A total of 147 infants from the United Kingdom were enrolled and randomly assigned to receive rMenB or rMenB+OMV at 2, 4, 6, and 12 months of age or a single dose at 12 months of age. Serum samples taken before and after vaccination were assayed in a standardized serum bactericidal antibody assay against 7 MenB strains. Local and systemic reactogenicity were recorded for 7 days after each vaccination. Analysis was according to protocol. RESULTS After 3 doses, both vaccines were immunogenic against strains expressing homologous or related NadA and fHBP. rMenB+OMV demonstrated greater immunogenicity than did rMenB and was immunogenic against strains expressing homologous PorA. Both vaccines elicited anamnestic responses after the fourth dose. For both vaccines, responses were lower against strains expressing heterologous fHBP variants and after a single dose at 12 months. CONCLUSIONS The rMenB+OMV vaccine has the potential to protect infants from MenB disease, although the breadth of protection afforded to heterologous antigens requires additional investigation.

Immunogenicity of two investigational serogroup B meningococcal vaccines in the first year of life: a randomized comparative trial.

Background: An investigational vaccine against serogroup B meningococcal (MenB) disease containing 3 main recombinant proteins (factor H-binding protein, Neisserial adhesion A, and Neisserial heparin-binding antigen) has been developed. We evaluated the immunogenicity and reactogenicity of a 3-dose course of this vaccine administered alone (recombinant MenB [rMenB]) or combined with the outer membrane vesicle (OMV) component of the vaccine used in New Zealand (rMenB+OMV). Methods: A randomized, single-blind, comparative study of 60 healthy infants enrolled at 6 to 8 months of age and immunized with rMenB or rMenB+OMV at day 0, day 60, and at age 12 months. Blood samples obtained at baseline and 1 month following the second and third doses of vaccine were analyzed for serum bactericidal antibody (SBA) using human complement (hSBA) against 7 MenB strains. The putative correlate of protection was an hSBA titer of ≥4. Results: The per-protocol analysis included 24 of 30 participants randomized to each group. After 3 doses of rMenB+OMV, 90% or more of participants had an hSBA titer ≥4 for 5 MenB strains, with 70% of participants having an hSBA titer ≥4 for a sixth strain. rMenB alone was immunogenic for only 3 strains. Both vaccines were well tolerated. Conclusions: Three doses of rMenB+OMV in the second half of infancy induce bactericidal antibodies against strains expressing vaccine antigens, demonstrating the potential for broader vaccine prevention of MenB disease. This vaccine is now in phase III clinical trials.

Safety and immunogenicity of AS03B adjuvanted split virion versus non-adjuvanted whole virion H1N1 influenza vaccine in UK children aged 6 months-12 years: open label, randomised, parallel group, multicentre study.

Objectives To compare the safety, reactogenicity, and immunogenicity of an adjuvanted split virion H1N1 vaccine and a non-adjuvanted whole virion vaccine used in the pandemic immunisation programme in the United Kingdom. Design Open label, randomised, parallel group, phase II study. Setting Five UK centres (Oxford, Southampton, Bristol, Exeter, and London). Participants Children aged 6 months to less than 13 years for whom a parent or guardian had provided written informed consent and who were able to comply with study procedures were eligible. Those with laboratory confirmed pandemic H1N1 influenza or clinically diagnosed disease meriting antiviral treatment, allergy to egg or any other vaccine components, or coagulation defects, or who were severely immunocompromised or had recently received blood products were excluded. Children were grouped by age: 6 months-<3 years (younger group) and 3-<13 years (older group). Recruitment was by media advertising and direct mailing. Recruitment visits were attended by 949 participants, of whom 943 were enrolled and 937 included in the per protocol analysis. Interventions Participants were randomised 1:1 to receive AS03B (tocopherol based oil in water emulsion) adjuvanted split virion vaccine derived from egg culture or non-adjuvanted whole virion vaccine derived from cell culture. Both were given as two doses 21 days apart. Reactogenicity data were collected for one week after immunisation by diary card. Serum samples were collected at baseline and after the second dose. Main outcome measures Primary reactogenicity end points were frequency and severity of fever, tenderness, swelling, and erythema after vaccination. Immunogenicity was measured by microneutralisation and haemagglutination inhibition assays. The primary immunogenicity objective was a comparison between vaccines of the percentage of participants showing seroconversion by the microneutralisation assay (fourfold rise to a titre of ≥1:40 from before vaccination to three weeks after the second dose). Results Seroconversion rates were higher after the adjuvanted split virion vaccine than after the whole virion vaccine, most notably in the youngest children (163 of 166 participants with paired serum samples (98.2%, 95% confidence interval 94.8% to 99.6%) v 157 of 196 (80.1%, 73.8% to 85.5%), P<0.001) in children under 3 years and 226 of 228 (99.1%, 96.9% to 99.9%) v 95.9%, 92.4% to 98.1%, P=0.03) in those over 3 years). The adjuvanted split virion vaccine was more reactogenic than the whole virion vaccine, with more frequent systemic reactions and severe local reactions in children aged over 5 years after dose one (13 (7.2%, 3.9% to 12%) v 2 (1.1%, 0.1% to 3.9%), P<0.001) and dose two (15 (8.5%, 4.8% to 13.7%) v 2 (1.1%, 0.1% to 4.1%), P<0.002) and after dose two in those under 5 years (15 (5.9%, 3.3% to 9.6%) v 0 (0.0%, 0% to 1.4%), P<0.001). Dose two of the adjuvanted split virion vaccine was more reactogenic than dose one, especially for fever ≥38ºC in those aged under 5 (24 (8.9%, 5.8% to 12.9%) v 57 (22.4%, 17.5% to 28.1%), P<0.001). Conclusions In this first direct comparison of an AS03B adjuvanted split virion versus whole virion non-adjuvanted H1N1 vaccine, the adjuvanted vaccine, while more reactogenic, was more immunogenic and, importantly, achieved high seroconversion rates in children aged less than 3 years. This indicates the potential for improved immunogenicity of influenza vaccines in this age group. Trial registration Clinical trials.gov NCT00980850; ISRCTN89141709.

Seroprotection against serogroup C meningococcal disease in adolescents in the United Kingdom: observational study

Objective To determine the persistence of bactericidal antibody titres following immunisation with serogroup C meningococcal glycoconjugate vaccine at age 6-15 years in order to examine changes in persistence of antibodies with age. Design Observational study. Setting Secondary and tertiary educational institutions in the United Kingdom. Participants Healthy adolescents aged 11-20 years previously immunised between 6 and 15 years of age with one of the three serogroup C meningococcal vaccines. Intervention Serum obtained by venepuncture. Main outcome measures Percentage of participants with (rabbit complement) serum bactericidal antibody titres of at least 1:8; geometric mean titres of serogroup C meningococcal serum bactericidal antibody. Results Five years after immunisation, 84.1% (95% confidence interval 81.6% to 86.3%) of 987 participants had a bactericidal antibody titre of at least 1:8. Geometric mean titres of bactericidal antibody were significantly lower in 11-13 year olds (147, 95% confidence interval 115 to 188) than in 14-16 year olds (300, 237 to 380) and 17-20 year olds (360, 252 to 515) (P<0.0001 for both comparisons). Within these age bands, no significant difference in geometric mean titres of bactericidal antibody between recipients of the different serogroup C meningococcal vaccines was seen. More than 70% of participants had received a vaccine from one manufacturer; in this cohort, geometric mean titres were higher in those immunised at aged 10 years or above than in those immunised before the age of 10. Conclusions Higher concentrations of bactericidal antibody are seen five years after immunisation with serogroup C meningococcal vaccine at age 10 years or above than in younger age groups, possibly owing to immunological maturation. This provides support for adolescent immunisation programmes to generate sustained protection against serogroup C meningococcal disease not only for the vaccine recipients but also, through the maintenance of herd immunity, for younger children.

Immunogenicity and reactogenicity of a 13-valent-pneumococcal conjugate vaccine administered at 2, 4, and 12 months of age: a double-blind randomized active-controlled trial.

Background: A 2-, 4-, and 12-month schedule of a novel 13-valent-pneumococcal conjugate vaccine (PCV13), containing serotype 1, 3, 4, 5, 6A, 6B 7F, 9V, 14, 18C, 19A, 19F, and 23F polysaccharides individually conjugated to CRM197 was evaluated in a randomized, double-blind, controlled infant study. Methods: Two hundred eighty-six healthy infants received PCV13 or the 7-valent-pneumococcal conjugate vaccine (PCV7) at 2, 4, and 12 months of age, alongside a serogroup C meningococcal (MenC) vaccine (2 and 4 months of age), DTaP-IPV-Hib (2, 3, and 4 months), and a Hib-MenC vaccine (12 months). Specific antibody responses were assessed at age 5, 12, and 13 months. Results: At 13 months of age, >97% of PCV13 recipients had pneumococcal serotype-specific serum IgG concentrations ≥0.35 &mgr;g/mL for each vaccine serotype except serotype 3 (88.2%), and at least 93% of PCV13 recipients had OPA titers ≥1:8 for each serotype. At 5 months, 110/114 (96.5%) of PCV13 recipients and 100/102 (98.0%) of PCV7 recipients had serum anti-PRP (Hib) IgG concentration ≥0.15 &mgr;g/mL (difference, 1.5%; CI, −7.1%–3.7%), while 119/120 (99.2%) and 117/118 (99.2%), respectively, had MenC serum bactericidal assay titers of ≥1:8. All PCV13 recipients and 110/113 (97.3%) of PCV7 recipients had IgG concentrations against fimbrial agglutinogens of ≥2.2 EU/mL; IgG concentrations for the remaining pertussis antigens were ≥5 EU/mL for all participants. Local reactions and systemic events were similar in the PCV13 and PCV7 groups. Conclusions: A 2-, 4-, and 12-month course of PCV13 was immunogenic for all 13 vaccine serotypes and was well tolerated.

The Magnitude of the Antibody and Memory B Cell Responses during Priming with a Protein-Polysaccharide Conjugate Vaccine in Human Infants Is Associated with the Persistence of Antibody and the Intensity of Booster Response

Rapid waning of anti-polysaccharide bactericidal Ab and vaccine effectiveness is observed following infant immunization with the serogroup C meningococcal (MenC) glycoconjugate vaccine. This is despite the demonstrable presence of immunological memory. Persistence of functional Ab, therefore, appears to be the key determinant of MenC conjugate vaccine effectiveness. Ab persistence is thought to depend in the short term on the survival of plasma cells generated during priming and in the longer term on the production of new Ab secreting cells from memory B cells. In this study, we found a strong association between the level of MenC-specific Ab and the frequency of memory B cells measured at 5 mo of age (1 mo after 3-dose primary immunization with MenC conjugate vaccine), and the persistence of functional Ab at one year of age. These findings suggest that these two parameters are good markers of B cell responses to priming and can be used as predictors of long term humoral immunity induced by glycoconjugate vaccines received in early infancy.

Antibody Persistence after Serogroup C Meningococcal Conjugate Immunization of United Kingdom Primary-School Children in 1999–2000 and Response to a Booster: A Phase 4 Clinical Trial

BACKGROUND After immunization with serogroup C meningococcal (MenC) conjugate vaccine, antibody responses and vaccine effectiveness are sustained in adolescents, in contrast to rapid waning in young children. We investigated the persistence of serum bactericidal antibody (SBA) titers in children 6 years after immunization with MenC vaccine (primed between 2 months and 6 years of age). The response to a Haemophilus influenzae type b-MenC conjugate (Hib-MenC) booster was also measured. METHODS A phase 4 clinical trial was conducted among 250 healthy 6-12-year-old children. SBA titers were measured before, 1 month after, and 1 year after Hib-MenC administration. The correlate of protection was an SBA titer of 8. RESULTS An SBA titer of 8 was observed in 61 (25% [95% confidence interval {CI}, 20%-30%]) of 244 participants (mean age, 9.1 years; mean interval since MenC immunization, 6.75 years). The proportion with an SBA titer of 8 and the SBA geometric mean titer increased with age, from 12% (95% CI, 4%-23%) to 48% (95% CI, 29%-67%) and from 2.90 (95% CI, 2.11-3.99) to 17.20 (95% CI, 6.80-43.5), respectively, from a mean age of 7.0 to 12.1 years. One month after the Hib-MenC booster, all participants had an SBA titer of 8, which was sustained in 99.6% at 1 year. CONCLUSIONS As a result of waning antibody, the majority of 6-12-year-old children in the United Kingdom have inadequate serological protection against MenC. The persistence of MenC immunity and the response to a Hib-MenC booster is dependent on age at priming. A booster was highly effective in this cohort and could sustain population immunity against MenC disease. Trial registration. Current Controlled Trials ( http://www.controlled-trials.com ) identifier: ISRCTN72858898 .

An outpatient, ambulant-design, controlled human infection model using escalating doses of Salmonella Typhi challenge delivered in sodium bicarbonate solution.

Oral delivery of escalating-dose Salmonella Typhi (Quailes strain) using sodium bicarbonate buffer solution in an outpatient, ambulant-design human infection study demonstrates safety, requires a lower challenge inoculum than that used in historical studies, and offers a unique insight into host–pathogen interactions.

Immunogenicity and immune memory of a nonadjuvanted quadrivalent meningococcal glycoconjugate vaccine in infants.

Background: The highest rate of invasive meningococcal disease is among children under 2 years of age. There is currently no licensed quadrivalent (serogroups A, C, W-135, and Y) meningococcal glycoconjugate vaccine approved for infants. We evaluated the immunogenicity and reactogenicity of a novel quadrivalent nonadjuvanted meningococcal glycoconjugate vaccine (MenACWY-CRM) in healthy infants. Methods: One hundred eighty infants (90 in Canada and 90 in the United Kingdom) received 2 doses of MenACWY-CRM at 2 and 4 months of age administered concomitantly with routine infant vaccines. At 12 months of age, the Canadian infants received either MenACWY-CRM or a reduced dose of a licensed meningococcal polysaccharide vaccine. In the United Kingdom, all infants received a further dose of MenACWY-CRM. The serological marker of protection was a titer of ≥1:4 using a serum bactericidal assay with human complement (hSBA). Results: Two doses of MenACWY-CRM induced hSBA titers ≥1:4 in 57% (95% confidence interval [CI]: 45–67) and 50% (95% CI: 38–62) of infants against serogroup A in Canada and the United Kingdom, respectively, 93% (95% CI: 85–97) and 86% (95% CI: 46–93) against serogroup C, 95% (95% CI: 87–99) and 82% (95% CI: 71–90) against serogroup W-135, and 91% (95% CI: 82–96) and 74% (95% CI: 63–83) against serogroup Y. After a booster dose of MenACWY-CRM at 12 months, at least 94% of participants achieved hSBA titers ≥1:4 against each of the serogroups C, W-135, and Y and more than 79% against serogroup A. The vaccine was well tolerated. Conclusions: The nonadjuvanted MenACWY-CRM is immunogenic and well tolerated in infancy and could provide broad protection against meningococcal disease in this vulnerable age group.