Immunogenicity and safety of a 13-valent pneumococcal conjugate vaccine in healthy infants in Japan

A phase 3 randomized study to evaluate safety and immunogenicity of 20-valent pneumococcal conjugate vaccine in healthy Japanese infants

OBJECTIVES

Safety and immunogenicity evaluation of a 4-dose series with 20-valent pneumococcal conjugate vaccine (PCV20).

METHODS

This phase 3, double-blind study randomized healthy Japanese infants to receive 4 doses (3 infant doses, 1 toddler dose) of PCV20 by subcutaneous (SC) or intramuscular (IM) injection or 13-valent PCV (PCV13) SC. A primary immunogenicity objective was to demonstrate noninferiority of PCV20 SC to PCV13 SC for percentages of participants meeting predefined serotype-specific immunoglobulin G concentrations 1 month after Dose 3. The 7 additional PCV20 serotypes were compared with the lowest vaccine serotype result in the PCV13 group. Safety and tolerability were assessed as the primary safety objective.

RESULTS

Overall, 668 participants were randomized (PCV20 SC, n = 226; PCV13 SC, n = 224; PCV20 IM, n = 218). The primary noninferiority objective for PCV20 SC to PCV13 SC was met for 11/13 matched and 5/7 additional serotypes. Additional data showed PCV20 SC and IM elicited robust functional opsonophagocytic activity and boosting responses to all 20 vaccine serotypes. PCV20 had a similar safety/tolerability profile to PCV13, although local reactions were less frequent with PCV20 IM.

CONCLUSIONS

A 4-dose series of PCV20 SC or IM elicited immune responses expected to be protective against all 20 serotypes in Japanese infants. NCT04530838.

Bacterial Meningitis Due to Streptococcus pneumoniae in a 7-Month-Old Girl Who Received Three Doses of 13-Valent Pneumococcal Conjugate Vaccine

In Japan, pneumococcal vaccine has been routinely administered since 2010 to prevent invasive pneumococcal diseases such as Streptococcus pneumoniae meningitis. We describe a case of pneumococcal meningitis in a 7-month-old girl who had received three doses of 13-valent pneumococcal conjugate vaccine. Brain magnetic resonance imaging showed infarcts in the right frontal region, and she was treated with antibiotics, intravenous immunoglobulin, dexamethasone, and edaravone. On day 27, an enhanced brain CT scan showed improvement of abnormal findings in the frontal region, except for slight atrophy. The S. pneumoniae serotype was 12F, which is not included in the 13-valent pneumococcal conjugate vaccine. A future vaccine is expected to use cross-reactivity to target common antigens.

Efficacy and Effectiveness of the PCV-10 and PCV-13 Vaccines Against Invasive Pneumococcal Disease

CONTEXT

Pneumococcal conjugate vaccines (PCVs) (pneumococcal 13-valent conjugate vaccine [PCV-13] and pneumococcal 10-valent conjugate vaccine [PCV-10]) are available for prevention of pneumococcal infections in children.

OBJECTIVE

To determine the vaccine effectiveness (VE) of PCV-13 and PCV-10 in preventing invasive pneumococcal disease (IPD) and acute otitis media (AOM) in children <5 years.

DATA SOURCES

Systematic searches of Medline, Embase, Cumulative Index to Nursing and Allied Health Literature, Web of Science, and Cochrane.

STUDY SELECTION

Eligible studies examined the direct effectiveness and/or efficacy of PCV-10 and PCV-13 in reducing the incidence of disease in healthy children <5 years.

DATA EXTRACTION

Two reviewers independently conducted data extraction and methodologic quality assessment.

RESULTS

Significant effectiveness against vaccine-type IPD in children ≤5 years was reported for ≥1 dose of PCV-13 in the 3 + 1 (86%-96%) and 2 + 1 schedule (67.2%-86%) and for PCV-10 for the 3 + 1 (72.8%-100%) and 2 + 1 schedules (92%-97%). In children <12 months of age, PCV-13 VE against serotype 19A post-primary series was significant for the 3 + 1 but not the 2 + 1 schedule. PCV-10 crossprotection against 19A was significant in children ≤5 years with ≥1 dose (82.2% and 71%). Neither PCVs were found effective against serotype 3. PCV-13 was effective against AOM (86%; 95% confidence interval [CI]: 61 to 94). PCV-10 was effective against clinically defined (26.9%; 95% CI: 5.9 to 43.3) and bacteriologically confirmed AOM (43.3%; 95% CI: 1.7 to 67.3).

LIMITATIONS

Because of the large heterogeneity in studies, a meta-analysis for pooled estimates was not done.

CONCLUSIONS

Both PCVs afford protection against pneumococcal infections, with PCV-10 protecting against 19A IPD, but this VE has not been verified in the youngest age groups.

Associations between geographic region and immune response variations to pneumococcal conjugate vaccines in clinical trials: A systematic review and meta-analysis

OBJECTIVE

Geographic region can be an important source of variation in the immune response to pneumococcal conjugate vaccines (PCV). The aim of this study was to collate data from available PCV clinical trials in order to characterize the differences in antibody responses in different countries.

METHODS

A systematic review and meta-analysis was conducted to examine the difference in antibody responses after primary series of PCVs in infants, associated with geographic regions, compared with each other and with the different PCVs using random-effects models.

RESULTS

A total of 69 trials were included. Studies conducted in the Western Pacific Region (WPR) showed higher geometric mean concentrations (GMC) compared to studies conducted in Europe. The pooled GMC for serotype 4 after three doses of PCV7 in the WPR was 5.19 μg/ml (95% confidence interval 4.85-5.53 μg/ml), while for studies conducted in Europe this was 2.01 μg/ml (95% confidence interval 1.88-2.14 μg/ml). The IgG GMC ratios among the WPR versus European regions ranged from 1.51 to 2.87 for PCV7, 1.69 to 3.22 for PCV10, and 1.49 to 3.08 for PCV13.

CONCLUSIONS

Studies conducted in the WPR generally showed greater antibody responses than the studies conducted in Europe. Indications of differences among geographic regions highlight the fact that further research is needed to compare the biological factors contributing to immune responses, which may affect vaccination schedules.

Evaluation of a Validated Luminex-Based Multiplex Immunoassay for Measuring Immunoglobulin G Antibodies in Serum to Pneumococcal Capsular Polysaccharides

This article describes the results of a study designed to bridge the World Health Organization (WHO) pneumococcal enzyme-linked immunosorbent assay (ELISA) platform to the validated Luminex-based 13-plex direct immunoassay (dLIA) platform developed by Pfizer, Inc. Both assay platforms quantify serotype-specific serum IgG antibodies (in micrograms per milliliter) against an international reference standard serum. The primary goal of this study was to determine if the dLIA is a suitable replacement for the ELISA to support clinical vaccine studies that include the evaluation of immune responses to serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F. Serum samples were selected from four pivotal 13-valent pneumococcal conjugate vaccine (13vPnC; Prevnar 13) clinical trials on the basis of their serotype-specific IgG concentrations by ELISA. In these studies, subjects were immunized either with 13vPnC or with 7-valent pneumococcal conjugate vaccine (7vPnC; Prevnar). There were 1,528 of 1,574 selected samples with sufficient remaining volume for reanalysis in the dLIA. A comparison of assay results from the dLIA and ELISA platforms showed clear and robust linear quantitative relationships across all 13 serotypes. In addition, lower IgG antibody concentrations in preimmunization samples were measured in the dLIA, thus allowing better differentiation between preimmunization and low-titer postimmunization samples. Overall, the results showed that the established population-level protective threshold IgG concentration, 0.35 µg/ml of serotype-specific serum IgG antibodies, is appropriate for use for data generated using the dLIA platform developed by Pfizer, Inc., for 10 serotypes: serotypes 1, 3, 4, 6A, 7F, 9V, 14, 18C, 19F, and 23F. On the basis of the extensive bridging analyses, however, the use of dLIA cutoff values of 0.23, 0.10, and 0.12 µg/ml is recommended for serotypes 5, 6B, and 19A, respectively. This adjustment will ensure that the consistency of the established population-level protective threshold IgG concentration is maintained when switching from the ELISA to the dLIA platform. The results of this bridging study demonstrate that the 13-plex dLIA platform is a suitable replacement for the WHO reference ELISA platform.IMPORTANCE The pneumococcal enzyme-linked immunosorbent assay (ELISA) measures IgG antibodies in human serum, and it is an important assay that supports licensure of pneumococcal vaccines. The immune correlate of protection, 0.35 µg/ml of IgG antibodies, was determined by the ELISA method. Pfizer has developed a new Luminex-based assay platform to replace the ELISA. These papers describe the important work of (i) validating the Luminex-based assay and (ii) bridging the immune correlate of protection (0.35 µg/ml IgG) to equivalent values reported by the Luminex platform.

Subcutaneous diphtheria and tetanus vaccines in children with haemophilia: A pilot study and review of the literature

INTRODUCTION

Subcutaneous (SQ) vaccination has emerged as standard of care in children with severe bleeding disorders to reduce unnecessary factor exposure and avoid provoking an intramuscular bleed, but little is known about comparative immunogenicity to intramuscular (IM) vaccination.

AIM

To confirm immunogenicity of Diphtheria Tetanus acellular Pertussis (DTaP) vaccines administered SQ to individuals <6 years old with haemophilia.

METHODS

We performed a retrospective and prospective pilot study of tetanus and diphtheria antibody titres among patients evaluated at our Haemophilia Treatment Centre between 2015-2016. Children with haemophilia who had received three to four doses of DTaP containing vaccine administered SQ were eligible.

RESULTS

Eight children met inclusion criteria. The mean age at the time of diphtheria and tetanus antibody testing was 21.1±17.8 months. All children who received SQ diphtheria and tetanus developed a positive antibody titre to both antigens. There was no statistically significant difference in distribution of titre values. The average time between the last dose of vaccine and antibody testing was 6.6±3.9 months among SQ vaccinated subjects. Minor injection site reactions were common with SQ vaccines.

CONCLUSION

SQ administration of diphtheria and tetanus vaccination appears to be immunogenic in a pilot study of Haemophilia patients and supports this practice as the standard of care for this population.

Invasive pneumococcal disease among adults in Japan, April 2013 to March 2015: disease characteristics and serotype distribution

BACKGROUND

In Japan, the clinical characteristics and recent serotype distribution among adult patients of invasive pneumococcal disease (IPD) have not been fully investigated since the introduction of the pneumococcal conjugate vaccine (PCV) in children. From November 2010, PCV7 was encouraged by an official program, funded by government, subsequently included in the routine schedule in April 2013, and replaced with a PCV13 in November 2013.

METHODS

Between April 2013 and March 2015, patients with IPD older than 15 years were evaluated based on the enhanced national surveillance in ten prefectures of Japan. The serotype distribution of the isolates was analyzed in these patients.

RESULTS

The analysis included 291 patients: 107 patients (37%) were female and the median age was 70 years. Of 281 patients with available data, 202 (72%) had underlying diseases, including 107 patients (38%) with immunocompromised status. The case fatality proportion for all case was 20%. In subgroup analysis, the case fatality proportion (29%) in immunocompromised patients was much higher than that (0-16%) in each age group of nonimmunocompromised patients (15-39 years, 40-64 years, and ≥ 65 years). While the proportion of bacteremia without any focus (27%) was higher than that (8-10%) in nonimmunocompromised patients, the proportions of vaccine types (PCV13, 32%; PPSV23, 51%) of the causative isolates were lower than those in each age group of nonimmunocompromised patients. Among 291 isolates, the most frequent serotypes were 3 (17%), 19A (13%), and 22F (10%). Twelve percent of the isolates were PCV7 serotypes, 46% were PCV13 serotypes, and 66% were PPSV23 serotypes.

CONCLUSIONS

The majority of adult patients of IPD had underlying diseases, including immunocompromised conditions. A low proportion (12%) of PCV7-type IPD was observed in this population where PCV7 for children had been included in the routine immunization schedule.

Analysis of Streptococcus pneumoniae and Haemophilus influenzae isolated from middle ear fluid before and after the introduction of government subsidies for pneumococcal and H. influenzae type b vaccines in Japan

This study aimed to identify trends in frequency, serotype, and antimicrobial susceptibility of Streptococcus pneumoniae and Haemophilus influenzae isolated from middle ear fluid specimens of children aged≤15 years (mean, 2 years), before and after the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) and the H. influenzae type b vaccine, at a pediatric facility in Japan. Sixty-six S. pneumoniae and 88 H. influenzae strains were isolated from 820 middle ear fluid samples. Serotyping and antimicrobial susceptibility testing were performed. The study time-frame was divided into period 1 (2007-2010) and period 2 (2011-2014), according to the availability of vaccine public funding. The S. pneumoniae detection rate decreased from 9.6% in period 1-6.1% in period 2 (p = 0.042). PCV7 serotypes decreased from 56.8% to 9.1% (p = 0.0002). No significant change was observed for the 13-valent pneumococcal conjugate vaccine (PCV13) serotypes: 72.7% in period 1 and 59.1% in period 2. Penicillin-resistant strains (penicillin G-MIC ≥2 μg/mL) decreased from 25% to 4.5% (p = 0.038). Detection rates for H. influenzae did not change significantly: 10.3% in period 1 and 11.3% in period 2. Serotypes were mostly non-typeable: 97.9% in period 1 and 90.2% in period 2, and only one serotype b strain was isolated in each period. The frequency of ampicillin-resistant strains (MIC ≥4 μg/mL) did not change. These results show a preventative effect of PCV7 on otitis media due to S. pneumoniae. PCV7 was replaced with PCV13 in 2013 in Japan; therefore, a further decrease in pneumococcal otitis media is anticipated in the future.

Immunogenicity and safety of the 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) co-administered with DTPa vaccine in Japanese children: A randomized, controlled study

This phase III, randomized, open-label, multicenter study (NCT01027845) conducted in Japan assessed the immunogenicity, safety, and reactogenicity of 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV, given intramuscularly) co-administered with diphtheria-tetanus-acellular pertussis vaccine (DTPa, given subcutaneously). Infants (N=360 ) were randomized (2:1) to receive either PHiD-CV and DTPa (PHiD-CV group) or DTPa alone (control group) as 3-dose primary vaccination (3–4–5 months of age) and booster vaccination (17–19 months of age). Immune responses were measured before and one month after primary/booster vaccination and adverse events (AEs) were recorded. Post-primary immune responses were non-inferior to those in pivotal/efficacy European or Latin American pneumococcal protein D-conjugate vaccine studies. For each PHiD-CV serotype, at least 92.6% of infants post-primary vaccination and at least 97.7% of children post-booster had pneumococcal antibody concentrations ≥0.2 μg/ml, and at least 95.4% post-primary and at least 98.1% post-booster had opsonophagocytic activity (OPA) titers ≥8 . Geometric mean antibody concentrations and OPA titers (except OPA titer for 6B) were higher post-booster than post-priming for each serotype. All PHiD-CV-vaccinated children had anti-protein D antibody concentrations ≥100 EL.U/ml one month post-primary/booster vaccination and all were seroprotected/seropositive against each DTPa antigen. Redness and irritability were the most common solicited AEs in both groups. Incidences of unsolicited AEs were comparable between groups. Serious AEs were reported for 47 children (28 in PHiD-CV group); none were assessed as vaccine-related. In conclusion, PHiD-CV induced robust immune responses and was well tolerated when co-administered with DTPa in a 3-dose priming plus booster regimen to Japanese children.

Predicting the impact of new pneumococcal conjugate vaccines: serotype composition is not enough

Streptococcus pneumoniae is a major cause of childhood morbidity and mortality worldwide. A heptavalent polysaccharide-protein conjugate vaccine (PCV) has proven highly effective in preventing pneumococcal disease in industrialized countries. Two higher-valent pneumococcal conjugate vaccines are now widely available, even in the poorest countries. These differ from each other in the number of serotypes and carrier proteins used for their conjugation. Some have assumed that the only meaningful clinical difference between PCV formulations is a function of the number of serotypes each contains. A careful review of recent clinical data with these and several unlicensed PCV formulations points to important similarities but also that some key properties of each vaccine likely differ from one another.

IgG levels against 13-valent pneumococcal conjugate vaccine serotypes in non pneumococcal conjugate vaccine immunized healthy Japanese and intravenous immunoglobulin preparations

No studies showed specific antibody levels against all serotypes covered by 13-valent pneumococcal conjugate vaccine (PCV13) among polyclonal intravenous immunoglobulin (IVIG) products. Our study aimed to assess whether we could expect the efficacy of IVIG therapy for invasive pneumococcal disease (IPD) and to clarify the age group which should be recommended for IVIG therapy in case of IPD. Serotype-specific immunoglobulin G (IgG) levels against PCV13 serotypes were measured in four IVIGs which were produced from Japanese donors who were not immunized with any pneumococcal conjugate vaccines (PCVs), and in the serum of 160 non-PCV immunized Japanese subjects, by enzyme-linked immunosorbent assay. The functional opsonic activities of the IVIGs against serotypes 6B and 19A were assessed by a multiplexed opsonophagocytic killing assay. Japanese infants aged <2 years had a geometric mean IgG concentration of <0.35 μg/ml against several serotypes. Serotype-specific IgG concentrations varied among IVIGs. In general, IgG antibodies against serotypes 6A, 14 and 19A were higher in each IVIG. Although opsonization indices also varied among preparations, each IVIG had the ability to opsonize both serotypes 6B and 19A. This study suggests that routine immunization with PCV is important for prevention of IPD, especially for children <2 years old and IVIGs might be effective for IPD patients.