Direct Comparison of Immunogenicity Induced by 10- or 13-Valent Pneumococcal Conjugate Vaccine around the 11-Month Booster in Dutch Infants

Serotype 3 Antibody Response and Antibody Functionality Compared to Serotype 19A Following 13-Valent Pneumococcal Conjugate Immunization in Children

BACKGROUND

Prevention of infections in children vaccinated with 13-valent pneumococcal conjugate vaccine (PCV13) may be less effective against serotype 3 than 19A.

OBJECTIVE

The aim of this study was to to determine differences in IgG and functional antibody for serotype 3 versus 19A following PCV13 immunization, in IgG antibody levels induced by PCV13 compared to naturally-induced immunity, and assess effectiveness of PCV13 against serotype 3 and 19A in prevention of acute otitis media (AOM) and colonization among 6-36-month-old children.

METHODS

Samples were from a prospective, longitudinal, observational cohort study conducted in Rochester, NY. Pneumococcal detection was by culture. 713 serum were tested for antibody levels by enzyme-linked immunosorbent assay, 68 for functional antibody by opsonophagocytosis and 47 for antibody avidity by thiocyanate bond disruption. PCV13 effectiveness in preventing AOM and colonization was determined by comparison of pre-PCV13 detection of serotypes 3 and 19A to post-PCV13.

RESULTS

The proportion of children who reached the antibody threshold of ≧0.35 µg/mL after PCV13 was higher for serotype 19A than serotype 3. Only serotype 19A showed significant increase in PCV13-induced opsonophagocytosis assay titers and antibody avidity. Serotype 3 naturally-induced immune children showed a positive trend of increase in antibody level as children got older, but not PCV13-immunized children. PCV13 effectiveness was not identified in preventing AOM or colonization for serotype 3 but effectiveness of 19A was confirmed.

CONCLUSIONS

PCV13 elicits lower antibody levels and lower effectiveness to serotype 3 versus serotype 19A. Post-PCV13-induced antibody levels for serotype 3 are likely insufficient to prevent AOM and colonization in most young children.

Development in the Concept of Bacterial Polysaccharide Repeating Unit-Based Antibacterial Conjugate Vaccines

The surface of cells is coated with a dense layer of glycans, known as the cell glycocalyx. The complex glycans in the glycocalyx are involved in various biological events, such as bacterial pathogenesis, protection of bacteria from environmental stresses, etc. Polysaccharides on the bacterial cell surface are highly conserved and accessible molecules, and thus they are excellent immunological targets. Consequently, bacterial polysaccharides and their repeating units have been extensively studied as antigens for the development of antibacterial vaccines. This Review surveys the recent developments in the synthetic and immunological investigations of bacterial polysaccharide repeating unit-based conjugate vaccines against several human pathogenic bacteria. The major challenges associated with the development of functional carbohydrate-based antibacterial conjugate vaccines are also considered.

Quality of antibody responses by adults and young children to 13-valent pneumococcal conjugate vaccination and Streptococcus pneumoniae colonisation

Childhood pneumococcal conjugate vaccine (PCV) protects against invasive pneumococcal disease caused by vaccine-serotype (VT) Streptococcus pneumoniae by generating opsonophagocytic anti-capsular antibodies, but how vaccination protects against and reduces VT carriage is less well understood. Using serological samples from PCV-vaccinated Malawian individuals and a UK human challenge model, we explored whether antibody quality (IgG subclass, opsonophagocytic killing, and avidity) is associated with protection from carriage. Following experimental challenge of adults with S. pneumoniae serotype 6B, 3/21 PCV13-vaccinees were colonised with pneumococcus compared to 12/24 hepatitis A-vaccinated controls; PCV13-vaccination induced serotype-specific IgG, IgG1, and IgG2, and strong opsonophagocytic responses. However, there was no clear relationship between antibody quality and protection from carriage or carriage intensity after vaccination. Similarly, among PCV13-vaccinated Malawian infants there was no relationship between serotype-specific antibody titre or quality and carriage through exposure to circulating serotypes. Although opsonophagocytic responses were low in infants, antibody titre and avidity to circulating serotypes 19F and 6A were maintained or increased with age. These data suggest a complex relationship between antibody-mediated immunity and pneumococcal carriage, and that PCV13-driven antibody quality may mature with age and exposure.

Salivary antibody responses to ten-valent pneumococcal conjugate vaccination following two different immunization schedules in a healthy birth cohort

Pneumococcal conjugate vaccines reduce pneumococcal colonization via serotype-specific immunoglobulin G (IgG) at mucosal surfaces. The infant immunization schedule with the ten-valent pneumococcal conjugate vaccine (PCV10) changed from a 3 + 1 schedule (2-3-4-11 months) to a 2 + 1 schedule (2-4-11 months) in The Netherlands in 2013. We compared anti-pneumococcal IgG concentrations in saliva between the schedules. IgG was measured using a fluorescent bead-based multiplex immunoassay at the ages of 6 (post-primary) and 12 (post-booster) months in 51 infants receiving the 3 + 1 schedule and 68 infants receiving the 2 + 1 schedule. Post-primary IgG geometric mean concentrations (GMCs) were comparable between schedules for all vaccine serotypes. Post-booster IgG GMCs were significantly lower after the 2 + 1 schedule for serotypes 4 (p = 0.035), 7F (p = 0.048) and 23F (p = 0.0056). This study shows small differences in mucosal IgG responses between a 3 + 1 and a 2 + 1 PCV10 schedule. Future studies should establish correlates of protection against pneumococcal colonization for mucosal antibodies.

Burden of invasive pneumococcal disease (IPD) over a 10-year period in Bogotá, Colombia

BACKGROUND

Invasive pneumococcal disease (IPD) is the leading cause of infectious death worldwide. This study aimed to describe the epidemiology of IPD and the impact of pneumococcal conjugate vaccine-10 (PCV-10) over a 10-year period in Bogotá, Colombia.

METHODS

This was a laboratory-based surveillance study of Streptococcus pneumoniae isolated from patients with IPD from 82 hospitals over 10 years in Bogotá, Colombia. Data were compared between two periods: 2007-2011 (before the introduction of PCV-10) and 2012-2017 (after the introduction of PCV-10).

RESULTS

In total, 1670 patients with IPD were included in the study between 2007 and 2017. Between 2007 and 2011, the most common serotypes were 14, 1, 6B, 6A and 3. Between 2012 and 2017, the most common serotypes were 19A, 3, 14 and 1. A decrease in the incidence of IPD, particularly in children aged 0-4 years, was noted after the introduction of PCV-10. Importantly, this reduction in incidence was not observed in patients aged ≥50 years.

CONCLUSIONS

The IPD burden in Bogotá remained stable between 2007 and 2017. The incidence of IPD decreased in children but not in older adults. The introduction of PCV-10 led to a change in the most prevalent serotypes to serotypes that are not included in PCV-10.

Cost-effectiveness analysis of replacing the 10-valent pneumococcal conjugate vaccine (PCV10) with the 13-valent pneumococcal conjugate vaccine (PCV13) in Brazil infants

Brazil currently has a 10-valent pneumococcal conjugate vaccine (PCV10) pediatric national immunization program (NIP). However, in recent years, there has been significant progressive increases in pneumococcal disease attributed to serotypes 3, 6A, and 19A, which are covered by the 13-valent PCV (PCV13). We sought to evaluate the cost-effectiveness and budget impact of switching from PCV10 to PCV13 for Brazilian infants from a payer perspective. A decision-analytic model was adapted to evaluate the clinical and economic outcomes of continuing PCV10 or switching to PCV13. The analysis estimated future costs ($BRL), quality-adjusted life-years (QALYs), and health outcomes for PCV10 and PCV13 over 5 y. Input parameters were from published sources. Future serotype dynamics were predicted using Brazilian and global historical trends. Over 5 y, PCV13 could prevent 12,342 bacteremia, 15,330 meningitis, 170,191 hospitalized pneumonia, and 25,872 otitis media cases, avert 13,709 pneumococcal disease deaths, gain 20,317 QALYs, and save 172 million direct costs compared with PCV10. The use of PCV13 in the Brazilian NIP could reduce pneumococcal disease, improve population health, and save substantial health-care costs. Results are reliable even when considering uncertainty for possible serotype dynamics with different underlying assumptions.

Association of Routine Infant Vaccinations With Antibody Levels Among Preterm Infants

IMPORTANCE

The standard schedule of national immunization programs for infants may not be sufficient to protect extremely and very preterm infants.

OBJECTIVE

To evaluate the immunogenicity of routine vaccinations administered to preterm infants.

DESIGN, SETTING, AND PARTICIPANTS

A multicenter, prospective, observational cohort study of preterm infants stratified according to gestational age recruited from 8 hospitals across the Netherlands between October 2015 and October 2017, with follow-up until 12 months of age (October 2018). In total, 296 premature infants were enrolled and compared with a control group of 66 healthy term infants from a 2011 study, immunized according to the same schedule with the same vaccines.

EXPOSURES

Three primary doses of the diphtheria-tetanus toxoids-acellular pertussis-inactivated poliomyelitis-Haemophilus influenza type b-hepatitis B combination vaccine were given at 2, 3, and 4 months after birth followed by a booster at 11 months and a 10-valent pneumococcal conjugate vaccine at 2, 4, and 11 months after birth.

MAIN OUTCOMES AND MEASURES

Primary end points were (1) proportion of preterm infants who achieved IgG antibody against vaccine antigens at concentrations above the internationally defined threshold for protection after the primary series and booster dose and (2) serum IgG geometric mean concentrations after the primary series and booster vaccination. Proportions and geometric mean concentrations were compared in preterm infants and the control group of term infants.

RESULTS

Of 296 preterm infants (56.1% male; mean gestational age, 30 weeks), complete samples before vaccination, 1 month after the primary series, and 1 month after the booster were obtained from 220 preterm infants (74.3%). After the primary series, the proportion of preterm infants across all gestational age groups who achieved protective IgG antibody levels against pertussis toxin, diphtheria, tetanus and 6 of 10 pneumococcal serotypes varied between 83.0% and 100%, Haemophilus influenzae type b between 34.7% and 46.2% (40.6% among all preterm infants overall), and pneumococcal serotypes 4, 6B, 18C, and 23F between 45.8% and 75.1%. After the booster dose, protective antibody levels were achieved in more than 95% of all preterm groups, except for Haemophilus influenzae type b (88.1%). In general, geometric mean concentrations of all vaccine-induced antibodies were significantly lower in all preterm infants vs term infants, except for pertussis toxin and pneumococcal serotypes 4 and 19F after the primary series and booster vaccination.

CONCLUSIONS AND RELEVANCE

Among preterm infants, administration of routine vaccinations during the first year of life was associated with protective antibody levels against most antigens in the majority of infants after the primary series and booster, except for Haemophilus influenzae type b. However, antibody concentrations were generally lower among preterm infants compared with historical controls.

Infant vaccine co-administration: review of 18 years of experience with GSK's hexavalent vaccine co-administered with routine childhood vaccines

INTRODUCTION

The benefits of vaccine co-administration include improved vaccine acceptance and uptake resulting in an increased coverage and protection against multiple childhood diseases, with minimal medical visits. The diphtheria-tetanus-acellular pertussis-hepatitis B-poliomyelitis-Haemophilus influenzae type b vaccine (DTaP-HBV-IPV/Hib) has been available for more than 19 years and is recommended for co-administration with several other infant vaccines.

AREAS COVERED

This is a comprehensive review (34 studies, 21,000 participants) describing the immunogenicity and safety of DTaP-HBV-IPV/Hib when co-administered with 12 different vaccines in infants including pneumococcal, meningococcal, rotavirus or measles-mumps-rubella-varicella.

EXPERT OPINION

Interactions among co-administered vaccines are complex. Therefore, co-administration data are critical before a vaccination regimen can be recommended. Co-administration of DTaP-HBV-IPV/Hib with other routinely administered vaccines was associated with high percentages of children achieving seroprotection/vaccine response against DTaP-HBV-IPV/Hib antigens. In addition, co-administration was not associated with clinically significant interference in immune responses to co-administered vaccines and was well tolerated. Increased systemic reactions observed with some combinations (DTaP-HBV-IPV/Hib + pneumococcal conjugate or meningococcal serogroup B vaccines) were mitigated by prophylactic paracetamol administration. The data reported here, which represent the most frequently used co-administrations of DTaP-HBV-IPV/Hib worldwide, support the concomitant administration of DTaP-HBV-IPV/Hib with other routinely recommended infant vaccines.

Synthetic carbohydrate-based vaccines: challenges and opportunities

Glycoconjugate vaccines based on bacterial capsular polysaccharides (CPS) have been extremely successful in preventing bacterial infections. The glycan antigens for the preparation of CPS based glycoconjugate vaccines are mainly obtained from bacterial fermentation, the quality and length of glycans are always inconsistent. Such kind of situation make the CMC of glycoconjugate vaccines are difficult to well control. Thanks to the advantage of synthetic methods for carbohydrates syntheses. The well controlled glycan antigens are more easily to obtain, and them are conjugated to carrier protein to from the so-call homogeneous fully synthetic glycoconjugate vaccines. Several fully glycoconjugate vaccines are in different phases of clinical trial for bacteria or cancers. The review will introduce the recent development of fully synthetic glycoconjugate vaccine.

Safety and immunogenicity of a novel 10-valent pneumococcal conjugate vaccine candidate in adults, toddlers, and infants in The Gambia-Results of a phase 1/2 randomized, double-blinded, controlled trial

BACKGROUND

A more affordable pneumococcal conjugate vaccine (PCV) that provides comparable protection to current PCVs is needed to ensure sustainable access in resource-limited settings. Serum Institute of India Pvt. Ltd.'s PCV candidate (SIIPL-PCV) has the potential to meet this need as manufacturing efficiency has been optimized and the vaccine targets the most prevalent disease-causing serotypes in Africa and Asia. We report SIIPL-PCV's safety, tolerability, and immunogenicity in adults, toddlers, and infants in The Gambia.

METHODS

This phase 1/2, randomized, double-blind trial sequentially enrolled 34 PCV-naive adults (18-40 years old), 112 PCV (Prevenar 13® [PCV13])-primed toddlers (12-15 months old), and 200 PCV-naive infants (6-8 weeks old), who were randomized (1:1) to receive SIIPL-PCV or a licensed comparator vaccine. Infants received three-doses of SIIPL-PCV or PCV13 at 6, 10, and 14 weeks of age co-administered with routine Expanded Program on Immunization (EPI) vaccines. Reactogenicity was solicited through seven-days post-vaccination; unsolicited adverse events (AEs) were assessed throughout the study. The safety and immunogenicity of a matching booster at 10-14 months of age were evaluated in a subset of 96 infants. Immune responses were evaluated post-primary and pre- and post-booster vaccinations.

RESULTS

Reactogenicity was primarily mild-to-moderate in severity. In infants, the most common solicited reactions were injection-site tenderness and fever, with no meaningful treatment-group differences. There were no serious or severe vaccine-related AEs and no meaningful trends in SAEs, vaccine-related AEs, or overall AEs. Infant post-primary seroresponse rates (IgG level ≥ 0.35 µg/mL) were ≥89% for all serotypes except 6A (79%) in the SIIPL-PCV group. IgG GMCs were >1 µg/mL for all serotypes in both SIIPL-PCV and PCV13 groups. Post-booster GMCs were comparable between groups.

CONCLUSION

SIIPL-PCV was well-tolerated, had an acceptable safety profile, and was immunogenic for all vaccine serotypes. Results support the evaluation of SIIPL-PCV in a phase 3 non-inferiority trial. Clinicaltrials.gov: NCT02308540.

Persistence of pneumococcal antibodies after primary immunisation with a polysaccharide-protein conjugate vaccine

INTRODUCTION

Despite immunisation, antibiotics and intensive care management, infection with Streptococcus pneumoniae remains a major cause of morbidity and mortality in children. The WHO currently recommends vaccinating infants with either a 3+0 schedule (6 weeks, 3-4 and 4-6 months of age) or 2+1 schedule (2 doses before 6 months of age, plus a booster dose at 9-15 months of age). This study investigated pneumococcal antibody responses, including persistence of antibodies, after immunisation of healthy infants with a 3+0 schedule.

METHODS

We measured pneumococcal antibody concentrations to all 13 antigens included in the 13-valent pneumococcal conjugate vaccine (PCV13) after immunisation with a 3+0 schedule in 91 infants at 7 months and in 311 infants at 13 months of age. The geometric mean concentrations (GMCs) and the proportion of infants with an antibody concentration above the standard threshold correlate of protection (seroprotection rate) were calculated at both time points.

RESULTS

At 7 months of age, GMCs varied between 0.52 µg/mLand 11.52 µg/mL, and seroprotection rates varied between 69% and 100%. At 13 months of age, GMCs had decreased to between 0.22 µg/mLand 3.09 µg/mL, with the lowest responses against serotype 4, followed by 19A, 3, 6B and 23F. Seroprotection rates at 13 months of age were below 90% for most serotypes, with the lowest rates for serotype 4 (23%) followed by 19A (50%), 23F (61%) and 6B (64%).

CONCLUSION

Our study shows that at 13 months of age, many infants vaccinated with a 3+0 schedule have pneumococcal antibody concentrations below the standard threshold correlate of protection. To optimise protection against pneumococcal disease through early childhood and to improve antibody persistence and indirect protective effects, immunisation schedules with booster doses might be necessary.

Relationship between immune response to pneumococcal conjugate vaccines in infants and indirect protection after vaccine implementation

Introduction: Streptococcus pneumoniae is a leading cause of morbidity and mortality worldwide. Widespread infant vaccination with pneumococcal conjugate vaccines (PCVs) substantially reduced vaccine-serotype pneumococcal disease by direct protection of immunized children and indirect protection of the community via decreased nasopharyngeal carriage and transmission. Essential to grasping the public health implications of pediatric PCV immunization is an understanding of how PCV formulations impact carriage. Areas covered: Using clinical evidence, this review examines how the immune response to PCVs is associated with subsequent nasopharyngeal carriage reduction in vaccinated infants and toddlers. By combining direct and indirect protection, carriage reduction results in a reduced spread of vaccine serotypes, and eventually, a decrease in vaccine serotype disease incidence in community members of all ages. Expert opinion: The current review presents some of the aspects that influence the overall impact of PCVs on vaccine-serotype carriage, and thus, spread. The link between reduction of vaccine-serotype carriage and the eventual reduction of vaccine-serotype disease in the wider community is described by comparing data from current PCVs, specifically with respect to their ability to reduce carriage of some cross-reacting serotypes (i.e. 6A versus 6B and 19A versus 19F).

Development and Standardization of a High-Throughput Multiplex Immunoassay for the Simultaneous Quantification of Specific Antibodies to Five Respiratory Syncytial Virus Proteins

In view of vaccine and monoclonal development to reduce hospitalization and death due to lower respiratory tract infection caused by RSV, assessment of antibody levels against RSV is essential. This newly developed multiplex immunoassay is able to measure antibody levels against five RSV proteins simultaneously. This can provide valuable insight into the dynamics of (maternal) antibody levels and RSV infection in infants and toddlers during the first few years of life, when primary RSV infection occurs.

Human respiratory syncytial virus (RSV) is a major cause of severe respiratory disease in (premature) newborns and causes respiratory illness in the elderly. Different monoclonal antibody (MAb) and vaccine candidates are in development worldwide and will hopefully become available within the near future. To implement such RSV vaccines, adequate decisions about immunization schedules and the different target group(s) need to be made, for which the assessment of antibody levels against RSV is essential. To survey RSV antigen-specific antibody levels, we developed a serological multiplex immunoassay (MIA) that determines and distinguishes antibodies against the five RSV glycoproteins postfusion F, prefusion F, Ga, Gb, and N simultaneously. The standardized RSV pentaplex MIA is sensitive, highly reproducible, and specific for the five RSV proteins. The preservation of the conformational structure of the immunodominant site Ø of prefusion F after conjugation to the beads has been confirmed. Importantly, good correlation is obtained between the microneutralization test and the MIA for all five proteins, resulting in an arbitrarily chosen cutoff value of prefusion F antibody levels for seropositivity in the microneutralization assay. The wide dynamic range requiring only two serum sample dilutions makes the RSV-MIA a high-throughput assay very suitable for (large-scale) serosurveillance and vaccine clinical studies.

IMPORTANCE In view of vaccine and monoclonal development to reduce hospitalization and death due to lower respiratory tract infection caused by RSV, assessment of antibody levels against RSV is essential. This newly developed multiplex immunoassay is able to measure antibody levels against five RSV proteins simultaneously. This can provide valuable insight into the dynamics of (maternal) antibody levels and RSV infection in infants and toddlers during the first few years of life, when primary RSV infection occurs.

Immunogenicity and reactogenicity of ten-valent versus 13-valent pneumococcal conjugate vaccines among infants in Ho Chi Minh City, Vietnam: a randomised controlled trial

Background

Few data are available to support the choice between the two currently available pneumococcal conjugate vaccines (PCVs), ten-valent PCV (PCV10) and 13-valent PCV (PCV13). Here we report a head-to-head comparison of the immunogenicity and reactogenicity of PCV10 and PCV13.

Methods

In this parallel, open-label, randomised controlled trial, healthy infants from two districts in Ho Chi Minh City, Vietnam, were randomly allocated (in a 3:3:5:4:5:4 ratio), with use of a computer-generated list, to one of six infant PCV schedules: PCV10 in a 3 + 1 (group A), 3 + 0 (group B), 2 + 1 (group C), or two-dose schedule (group D); PCV13 in a 2 + 1 schedule (group E); or no infant PCV (control; group F). Blood samples were collected from infants between 2 months and 18 months of age at various timepoints before and after PCV doses and analysed (in a blinded manner) by ELISA and opsonophagocytic assay. The trial had two independent aims: to compare vaccination responses between PCV10 and PCV13, and to evaluate different schedules of PCV10. In this Article, we present results pertaining to the first aim. The primary outcome was the proportion of infants with an IgG concentration of at least 0·35 μg/mL for the ten serotypes common to the two vaccines at age 5 months, 4 weeks after the two-dose primary vaccination series (group C vs group E, per protocol population). An overall difference among the schedules was defined as at least seven of ten serotypes differing in the same direction at the 10% level. We also assessed whether the two-dose primary series of PCV13 (group E) was non-inferior at the 10% level to a three-dose primary series of PCV10 (groups A and B). This trial is registered with ClinicalTrials.gov, number NCT01953510.

Findings

Of 1424 infants screened between Sept 30, 2013, and Jan 9, 2015, 1201 were allocated to the six groups: 152 (13%) to group A, 149 (12%) to group B, 250 (21%) to group C, 202 (17%) to group D, 251 (21%) to group E, and 197 (16%) to group F. 237 (95%) participants in group C (PCV10) and 232 (92%) in group E (PCV13) completed the primary vaccination series and had blood draws within the specified window at age 5 months, at which time the proportion of infants with IgG concentrations of at least 0·35 μg/mL did not differ between groups at the 10% level for any serotype (PCV10–PCV13 risk difference −2·1% [95% CI −4·8 to −0·1] for serotype 1; −1·3% [–3·7 to 0·6] for serotype 4; −3·4% [–6·8 to −0·4] for serotype 5; 15·6 [7·2 to 23·7] for serotype 6B; −1·3% [–3·7 to 0·6] for serotype 7F; −1·6% [–5·1 to 1·7] for serotype 9V; 0·0% [–2·7 to 2·9] for serotype 14; −2·1% [–5·3 to 0·9] for serotype 18C; 0·0% [–2·2 to 2·3] for serotype 19F; and −11·6% [–18·2 to −4·9] for serotype 23F). At the same timepoint, two doses of PCV13 were non-inferior to three doses of PCV10 for nine of the ten shared serotypes (excluding 6B). Reactogenicity and serious adverse events were monitored according to good clinical practice guidelines, and the profiles were similar in the two groups.

Interpretation

PCV10 and PCV13 are similarly highly immunogenic when used in 2 + 1 schedule. The choice of vaccine might be influenced by factors such as the comparative magnitude of the antibody responses, price, and the relative importance of different serotypes in different settings.

Funding

National Health and Medical Research Council of Australia, and Bill & Melinda Gates Foundation.

Maternal pertussis vaccination and its effects on the immune response of infants aged up to 12 months in the Netherlands: an open-label, parallel, randomised controlled trial

BACKGROUND

Maternal tetanus, diphtheria, and acellular pertussis (Tdap) vaccination offers protection for neonates against clinical pertussis until primary vaccinations, but maternal antibodies also interfere with infants' immune responses to primary vaccinations. We investigated the effect of maternal Tdap vaccination on the pertussis antibody responses of infants starting primary vaccinations at age 3 months.

METHODS

In an open-label, parallel, randomised, controlled trial, pregnant women aged 18-40 years with a low risk of pregnancy complications were recruited through independent midwives at 36 midwife clinics in the Netherlands and received Tdap vaccination either at 30-32 weeks of pregnancy (maternal Tdap group) or within 48 h after delivery (control group). All term-born infants were vaccinated with the diphtheria, tetanus, and pertussis-inactivated poliomyelitis-Haemophilus influenzae type B-hepatitis B six-in-one vaccine and a ten-valent pneumococcal vaccine at 3 months, 5 months, and 11 months. Randomisation was done using a number generator in a 1:1 ratio and with sealed envelopes. Participants and clinical trial staff were not masked, but laboratory technicians were unaware of study group assignments. The primary endpoint was serum IgG pertussis toxin antibody concentrations at age 3 months. Cord blood and infant blood samples were collected at age 2 months, 3 months, 6 months, 11 months, and 12 months. Analysis was done by modified intention to treat with all randomly assigned participants in case a laboratory result was available. This trial is registered with ClinicaltTrialsRegister.eu (EudraCT 2012-004006-9) and trialregister.nl (NTR number NTR4314). The trial is now closed to new participants.

FINDINGS

Between Jan 16, 2014, and March 4, 2016, 118 pregnant women were enrolled into our study, with 58 in the maternal Tdap group and 60 in the control group. The geometric mean concentration (GMC) of pertussis toxin antibodies were higher in infants in the maternal Tdap group than in the control group infants at age 3 months (GMC ratio 16·6, 95% CI 10·9-25·2) and also significantly higher compared with control infants at age 2 months. After primary vaccinations, antibody concentrations for pertussis toxin, filamentous haemagglutinin, and pertactin were significantly lower at all timepoints in infants of the maternal Tdap group than in infants in the control group. No safety issues after maternal Tdap vaccination were encountered.

INTERPRETATION

In view of the high pertussis toxin antibody concentrations at age 3 months, maternal vaccination supports a delay of the first pertussis vaccination in infants until at least age 3 months. Maternal antibody interference affects antibody concentrations after primary and booster vaccinations. The clinical consequences of this interference remain to be established.

FUNDING

The Dutch Ministry of Health, Welfare, and Sport.

Serotype-Specific IgG Antibody Waning after Pneumococcal Conjugate Primary Series Vaccinations with either the 10-Valent or the 13-Valent Vaccine

The two currently available ten- and thirteen-valent pneumococcal conjugate vaccines (PCV10 and PCV13) both induce serotype-specific IgG anti-polysaccharide antibodies and are effective in preventing vaccine serotype induced invasive pneumococcal disease (IPD) as well as in reducing overall vaccine-serotype carriage and transmission and thereby inducing herd protection in the whole population. IgG levels decline after vaccination and could become too low to prevent carriage acquisition and/or pneumococcal disease. We compared the levels of 10-valent (PCV10) and 13-valent (PCV13) pneumococcal vaccine induced serum IgG antibodies at multiple time points after primary vaccinations. Data from two separate studies both performed in the Netherlands in infants vaccinated at 2, 3, and 4 months of age with either PCV10 or PCV13 were compared. Antibody levels were measured at 5, 8, and 11 months of age, during the interval between the primary immunization series and the 11-months booster dose. Serotype-specific IgG levels were determined by multiplex immunoassay. Although antibody kinetics showed significant variation between serotypes and between vaccines for the majority of the 10 shared serotypes, i.e., 1, 5, 7F, 9V, 14, 18C, and 23F, antibody concentrations were sufficiently high for both vaccines, immediately after the primary series and throughout the whole period until the booster dose. In contrast, for serotypes 4 and 19F in the PCV10 group and for serotypes 4 and 6B in the PCV13 group, IgG antibody concentrations already come within reach of the frequently used seroprotection level of 0.35 μg/mL immediately after the primary series at the five month time point and/or at eight months. This paper addresses the importance of revealing differences in serotype-specific and pneumococcal vaccine-dependent IgG antibody patterns during the interval between the primary series and the booster dose, an age period with a high IPD incidence. Trial registration: www.trialregister.nl NTR3069 and NTR2316.

Safety and immunogenicity of the Cuban heptavalent pneumococcal conjugate vaccine in healthy infants. Results from a double-blind randomized control trial Phase I

BACKGROUND

Cuba has a new pneumococcal conjugate vaccine candidate (PCV7-TT). This study evaluates the safety and immunogenicity in healthy infants using 2p+1 vaccination schedule.

METHODS

A phase I, controlled, randomized and double blind clinical trial was designed. 30 unvaccinated healthy infants were included. 20 subjects were assigned to study group (PCV7-TT) and 10 to control group (Synflorix®) to receive the vaccines at 7, 8 months of age (primary series) and 11 months (booster dose). Blood samples were collected 30 days after second dose and post booster for antibodies measure analysis by ELISA and OPA. The statistics analysis included the frequency of occurrence for adverse events and the immune response. Non-parametric tests were used to compare the immune response. The clinical trial was published in the Cuban Public Register of Clinical Trials with code RPCEC00000173 available at http://registroclinico.sld.cu.

RESULTS

Overall, the safety profile of PCV7-TT was similar to Synflorix®. Local reactions were predominant and systemic events were mild in severity. Swelling and redness were frequently associated with PCV7-TT mainly after the first dose (50% and 40% respectively). 15% and 10% of subject reported severe swelling after first dose with PCV7-TT and after second dose with Synflorix®. Mild fever (≥38-≤39), vomiting and sleep disturb were the systemic events reported. 100% of infants achieved pneumococcal IgG antibody concentrations ≥0.35 µg/ml after booster dose for serotypes 1, 14, 18C and 19F in each vaccine group. For serotypes 5, 6B and 23F, more than 80% infants vaccinated with Synflorix® or PCV7-TT achieved protective IgG GMC ≥ 0.35 µg/ml after booster dose. OPA proportion's responders to the seven common serotypes were 89.5% or more after the primary dose and 100% after booster dose in vaccinated with PCV7-TT.

CONCLUSIONS

The Cuban PCV7-TT is safe, well tolerated and immunogenic in healthy infants.

Cost-effectiveness analysis of routine 13-valent pneumococcal conjugate vaccinations in Chinese infants

BACKGROUND

This study aimed to evaluate the cost-effectiveness of the 13-valent pneumococcal conjugate vaccine (PCV-13) compared to a no vaccination strategy in Chinese infants.

METHODS

A Markov process model was developed to examine the outcomes of PCV-13 against a no vaccination strategy using data and assumptions adapted for relevance to China. Outcomes over a lifetime horizon are presented. One-way and probabilistic sensitivity analyses were performed to determine the uncertainty.

RESULTS

Compared to no vaccination, a PCV-13 vaccination program would provide a gain of 0.009 additional quality-adjusted life years (QALYs) per subject. From the health care and societal perspectives, the incremental costs per QALY were $20,709 and 18,483, respectively. When herd effect was included, the cost effectiveness of the PCV-13 vaccination strategy was notably improved. The lower price of PCV-13 will improve the cost-effectiveness.

CONCLUSIONS

The PCV-13 vaccination is likely to be cost-effective at the current Chinese prices and ceiling threshold ($8,382).

Increased carriage of non-vaccine serotypes with low invasive disease potential four years after switching to the 10-valent pneumococcal conjugate vaccine in The Netherlands

The 7-valent pneumococcal conjugate vaccine (PCV7) was introduced in The Netherlands in 2006 and was replaced by PHiD-CV10 in 2011. Data on carriage prevalence of S. pneumoniae serotypes in children and invasive pneumococcal disease (IPD) in children and older adults were collected to examine the impact of PCVs on carriage and IPD in The Netherlands. Pneumococcal carriage prevalence was determined by conventional culture of nasopharyngeal swabs in 24-month-old children in 2015/2016. Data were compared to similar carriage studies in 2005 (pre-PCV7 introduction), 2009, 2010/2011 and 2012/2013. Invasive pneumococcal disease isolates from hospitalized children <5 years and adults >65 years (2004–2016) were obtained by sentinel surveillance. All isolates were serotyped by Quellung. Serotype invasive disease potential was calculated using carriage and nationwide IPD data in children. The overall pneumococcal carriage rate was 48% in 2015/2016, lower than in 2010/2011 (64%) and pre-vaccination in 2005 (66%). Carriage of the previously dominant non-vaccine serotypes 19A and 11A has declined since 2010/2011, from 14.2% to 4.6% and 4.2% to 2.7%, respectively, whereas carriage of serotypes 6C and 23B has increased (4.2% to 6.7% and 3.9% to 7.3%), making serotypes 6C and 23B the most prevalent carriage serotypes. IPD incidence declined in children (20/100,000 cases in 2004/2006 to 6/100,000 cases in 2015/2016) as well as in older adults (63/100,000 cases to 51/100,000 cases). Serotypes 6C, 23B and 11A have high carriage prevalence in children, but show low invasive disease potential. Serotype 8 is the main causative agent for IPD in older adults (11.3%). In conclusion, 10 years after the introduction of pneumococcal vaccination in children in The Netherlands shifts in carriage and disease serotypes are still ongoing. Surveillance of both carriage and IPD is important to assess PCV impact and to predict necessary future vaccination strategies in both children and older adults.

Differences by sex in IgG levels following infant and childhood vaccinations: An individual participant data meta-analysis of vaccination studies

BACKGROUND

If immune responses to vaccination differ between males and females, sex-specific vaccination schedules may be indicated. We systematically reanalysed childhood vaccination studies conducted in The Netherlands for sex-differences in IgG-responses. To assess the impact of potential sex-differences in IgG-responses, we explored sex-differences in vaccine failure/effectiveness and reactogenicity.

METHODS

Six studies with IgG-measurements for 1577 children following infant pneumococcal (PCV7/PCV10/PCV13) and/or DTaP-IPV-Hib(-HepB) vaccinations, or the pre-school DTaP-IPV booster were included. We performed one-stage individual participant data meta-analyses per time-point of the effect of sex on IgG levels against pneumococcal serotypes, diphtheria toxoid, tetanus toxoid, pertussis Ptx/FHA/Prn and Hib-PRP using linear mixed models. Using existing study data, we compared reactogenicity after PCV7/PCV10 and DTaP-IPV-Hib(-HepB) vaccination in girls and boys. Vaccine failure/effectiveness was compared between girls and boys for invasive pneumococcal disease (IPD), invasive Hib disease and pertussis using notification data.

RESULTS

For pneumococcal vaccination, the geometric mean concentration ratio of IgG levels in girls versus boys pooled across serotypes was 1.15 (95%CI 0.91-1.45) 1 month following the primary series, 1.16 (1.02-1.32) at age 8 months, 1.12 (1.02-1.23) pre-booster (age 11 months) and 0.99 (0.89-1.10) post-booster (age 12 months). Diphtheria toxoid, tetanus toxoid, pertussis Ptx/FHA/Prn and Hib-PRP IgG levels did not differ between girls and boys, except for Hib post-booster (1.24; 95%CI 1.01-1.52) and tetanus before pre-school booster (0.71; 0.53-0.95). We found no difference between boys and girls in reactogenicity at age 4 or 11 months or in vaccine failure/effectiveness for IPD, invasive Hib disease or pertussis.

CONCLUSION

For most vaccine antigens investigated, there were no consistent differences in vaccine-induced IgG levels. Vaccine-induced pneumococcal IgG levels were slightly higher in girls, but only between the primary series and the 11-month booster. These results, along with similar reactogenicity and vaccine failure/effectiveness, support the uniform infant vaccination schedule in the Dutch national immunisation programme.

Effectiveness of the 13-valent pneumococcal conjugate vaccine in preventing invasive pneumococcal disease in children aged 7-59 months. A matched case-control study

Background

The 13-valent pneumococcal conjugate vaccine (PCV13) was licensed based on the results of immunogenicity studies and correlates of protection derived from randomized clinical trials of the 7-valent conjugate pneumococcal vaccine. We assessed the vaccination effectiveness (VE) of the PCV13 in preventing invasive pneumococcal disease (IPD) in children aged 7–59 months in a population with suboptimal vaccination coverage of 55%.

Methods

The study was carried out in children with IPD admitted to three hospitals in Barcelona (Spain) and controls matched by hospital, age, sex, date of hospitalization and underlying disease. Information on the vaccination status was obtained from written medical records. Conditional logistic regression was made to estimate the adjusted VE and 95% confidence intervals (CI).

Results

169 cases and 645 controls were included. The overall VE of ≥1 doses of PCV13 in preventing IPD due to vaccine serotypes was 75.8% (95% CI, 54.1–87.2) and 90% (95% CI, 63.9–97.2) when ≥2 doses before 12 months, two doses on or after 12 months or one dose on or after 24 months, were administered. The VE of ≥1 doses was 89% (95% CI, 42.7–97.9) against serotype 1 and 86.0% (95% CI, 51.2–99.7) against serotype 19A. Serotype 3 showed a non-statistically significant effectiveness (25.9%; 95% CI, -65.3 to 66.8).

Conclusions

The effectiveness of ≥1 doses of PCV13 in preventing IPD caused by all PCV13 serotypes in children aged 7–59 months was good and, except for serotype 3, the effectiveness of ≥1 doses against the most frequent PCV13 serotypes causing IPD was high when considered individually.

Immunogenicity and safety of a booster dose of the 13-valent pneumococcal conjugate vaccine in children primed with the 10-valent or 13-valent pneumococcal conjugate vaccine in the Czech Republic and Slovakia

BACKGROUND

Although both the 13-valent pneumococcal conjugate vaccine (PCV13) and the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) are widely used, it is unclear how interchangeable they are in terms of immunogenicity.

METHODS

Two phase 3, open-label, multicenter studies were conducted to assess the immunogenicity and safety of a booster dose of PCV13 in children primed with PHiD-CV or PCV13. In the Czech Republic, 12-15-month-old children received a PCV13 booster after 3-dose priming with either PHiD-CV or PCV13. In Slovakia, 11-12-month-old children received PCV13 following 2-dose priming with either PHiD-CV or PCV13. Serum IgG concentrations were assessed by enzyme-linked immunosorbent assay and functional antibodies were assessed by opsonophagocytic assay (OPA) before the booster and at 1 and 12months afterward. The primary objective of these studies was to assess non-inferiority of OPA titers for serotype 19A in PHiD-CV-primed subjects compared to those in PCV13-primed children 1month post-booster.

RESULTS

A total of 98 subjects in the Czech Republic and 89 subjects in Slovakia were included. One month after the PCV13 booster dose, the IgG and OPA immune responses to serotype 19A in subjects primed with 2 or 3 doses of PHiD-CV were non-inferior to those in subjects primed with PCV13. Non-inferior and persistent immune responses to most other vaccine serotypes were also observed after the PCV13 booster in PHiD-CV-primed subjects. No safety issues were raised in either study.

CONCLUSIONS

Overall, robust IgG and OPA immunological responses were observed after booster vaccination with PCV13 in children primed with 2 or 3 doses of PHiD-CV or PCV13, including for serotypes not included in PHiD-CV. These results suggest that these vaccines are interchangeable in terms of safety and immunogenicity and that PCV13 can be used as a booster in the context of mixed schedules. (EudraCT numbers: 2012-005366-35 and 2012-005367-27).

Divergent Memory B Cell Responses in a Mixed Infant Pneumococcal Conjugate Vaccine Schedule

BACKGROUND

Vaccine-induced immunity against pneumococcal infection relies on the generation of high concentrations of antibody and B cell memory. Both the 10- and the 13-valent pneumococcal conjugate vaccines (PCV-10 and PCV-13) effectively reduce disease caused by vaccine serotypes. It is unknown whether the generation of B cell memory requires several doses of the same vaccine or whether different PCVs are interchangeable.

METHODS

Children in the United Kingdom (n=178) who had previously received PCV-13 at 2 and 4 months were randomized 1:1 to receive a PCV-13 or PCV-10 booster at age 12 months. Peripheral blood memory B cells (BMEM) were quantified before and at 1 and 12 months after vaccination using a cultured enzyme-linked immunospot assay for pneumococcal serotypes 1, 3, 4, 9V, 14, 19A, and diphtheria and tetanus toxoid. Correlations between BMEM frequencies and simultaneously measured antibody (IgG and opsonophagocytic assay) was also assessed.

RESULTS

A significant rise in postbooster BMEM frequency was seen for 5 out of 6 serotypes in the PCV-13 group and none in the PCV-10 group. In the PCV-13 group, there was a particularly large increase in serotype 3-specific BMEM associated with only a small increase in antibody. Postbooster BMEM responses correlated positively with antibody, but correlations between prebooster BMEM and subsequent BMEM and antibody responses were inconsistent.

CONCLUSIONS

After priming with PCV-13 in early infancy, a booster dose of PCV-10 does not induce detectable peripheral blood BMEM responses but a PCV-13 booster does induce robust responses. Booster responses to PCVs may be dependent on homologous carrier protein priming.

Prevention of Community-Acquired Pneumonia with Available Pneumococcal Vaccines

Community-acquired pneumonia (CAP) places a considerable burden on society. A substantial number of pediatric and adult CAP cases are due to Streptococcus pneumoniae, but fortunately there are effective vaccines available that have a significant impact on CAP-related medical, social, and economic problems. The main aim of this paper is to evaluate the published evidence concerning the impact of pneumococcal vaccines on the prevention of CAP in children and adults. Available data indicate that pneumococcal conjugate vaccines (PCVs) are effective in children, reducing all-cause CAP cases and bacteremic and nonbacteremic CAP cases. Moreover, at least for PCV7 and PCV13, vaccination of children is effective in reducing the incidence of CAP among adults. Recently use of PCV13 in adults alone or in combination with the pneumococcal polysaccharide vaccine has been suggested and further studies can better define its effectiveness in this group of subjects. The only relevant problem for PCV13 is the risk of a second replacement phenomenon, which might significantly reduce its real efficacy in clinical practice. Protein-based pneumococcal vaccines might be a possible solution to this problem.

The Antibody Response Following a Booster With Either a 10- or 13-valent Pneumococcal Conjugate Vaccine in Toddlers Primed With a 13-valent Pneumococcal Conjugate Vaccine in Early Infancy

BACKGROUND

Both the 13- and 10-valent pneumococcal conjugate vaccines (PCV-13; PCV-10) are immunogenic and effective against vaccine-type pneumococcal disease when given to young children. However, limited data are available regarding the interchangeability of these 2 vaccines.

METHODS

UK children (n = 178) who had previously been vaccinated with PCV-13 at 2 and 4 months were randomized to receive either a PCV-13 or a PCV-10 booster at 12 months of age. PCV-13 vaccine-type antipolysaccharide serum immunoglobulin G (IgG) concentrations and opsonophagocytic assay titers were measured before and at 1 and 12 months following vaccination. The primary objective was to assess noninferiority of PCV-10 compared with PCV-13.

RESULTS

For 8 of the PCV-10 serotypes at least 97% of participants in both groups had IgG concentrations ≥0.35 µg/mL at 1 month after vaccination; inferior responses were seen for serotypes 5 and 9V following the PCV-10 compared with the PCV-13 booster. Post booster geometric mean IgG concentrations and opsonophagocytic assay titers were significantly superior for most serotypes in PCV-13 compared with PCV-10 recipients, whereas similar or inferior responses were seen for serotypes 4, 18C, and 19F. Although some increase in antibody was seen in PCV-10 recipients against the serotypes 6A and 19A (serotypes that cross-react with 6B and 19F in PCV-10, respectively) at 1-month post booster, these responses were significantly lower than in the PCV-13 group.

CONCLUSIONS

In PCV-13 primed infants, a PCV-10 booster is generally less immunogenic than a PCV-13 booster. For the 3 serotypes in PCV-10 with higher antigen content and/or conjugation to diphtheria or tetanus toxoid carrier proteins, higher or similar booster responses were seen in PCV-10 recipients. Although these findings suggest that responses are generally better with a PCV-13 booster among PCV-13 primed children, the clinical significance of these differences in immunogenicity is unclear.