Review of 8 years of experience with Infanrix hexa (DTPa-HBV-IPV/Hib hexavalent vaccine)

A worldwide overview for hexavalent vaccines and a glimpse into Turkiye's perspective

The surge in recommended vaccinations for child's has spurred the development of combination vaccines, notably hexavalent vaccines, which provide multiple immunizations in a single dose. These vaccines offer various advantages, such as streamlining vaccination schedules, minimizing injection-related pain and exposure to preservatives, expanding vaccine coverage, and reducing administration costs. However, the intricate and expensive development of these vaccines presents substantial challenges, requiring increased investment and healthcare provider education to optimize their utilization and sustain high vaccination rates. Turkey, known for its robust vaccine coverage, strategic geographic location, and the influx of refugees, is at a critical juncture for integrating hexavalent vaccines into national programs. This transition is especially relevant given the rising vaccine hesitancy and the potential resurgence of vaccine-preventable diseases. This review assesses the deployment of hexavalent vaccines, examining their benefits and challenges through clinical trials and global experiences, with a specific emphasis on Turkiye's public health context.

Hexavalent vaccines in infants: a systematic literature review and meta-analysis of the solicited local and systemic adverse reactions of two hexavalent vaccines

Introduction: The hexavalent vaccine DT3aP-HBV-IPV-Hib (Infanrix hexa, GSK) was first licensed in Europe in 2000. DT2aP-HBV-IPV-Hib (Hexyon/Hexacima/Hexaxim, Sanofi Pasteur), and DT5aP-HBV-IPV-Hib (Vaxelis, MCM Vaccine Company) were licensed in the EU in 2013 and 2016, respectively, based largely on studies demonstrating non-inferiority to DT3aP-HBV-IPV-Hib for immunogenicity and comparable reactogenicity profiles.Methods: We conducted a systematic literature review looking for direct head-to-head trials comparing DT2aP-HBV-IPV-Hib and DT5aP-HBV-IPV-Hib with DT3aP-HBV-IPV-Hib. The incidence of solicited local and systemic reactions following primary series administration of DT3aP-HBV-IPV-Hib or DT2aP-HBV-IPV-Hib were meta-analyzed.Results: A total of 317 unique records were retrieved from the search; nine met the predefined inclusion criteria; seven reported studies comparing DT3aP-HBV-IPV-Hib and DT2aP-HBV-IPV-Hib. Six trials assessing outcomes of the primary vaccination series were identified. Odds ratios and 95% confidence intervals (OR; 95%CI) were computed for DT3aP-HBV-IPV-Hib, using DT2aP-HBV-IPV-Hib as reference, for redness (0.72; 0.63-0.83), pain (0.74; 0.62-0.89), swelling (0.86; 0.74-0.99) at injection site, fever (0.67; 0.54-0.83), persistent crying (0.72; 0.61-0.84), drowsiness (0.82; 0.71-0.94), irritability (0.82; 0.69-0.98), anorexia (0.83; 0.72-0.95), and vomiting (0.96; 0.83-1.11).Conclusion: ORs of analyzed local and systemic solicited adverse reactions after primary vaccination with DT3aP-HBV-IPV-Hib appear to be slightly lower than with DT2aP-HBV-IPV-Hib.

Control of vaccine preventable diseases in Australian infants: reviewing a decade of experience with DTPa-HBV-IPV/Hib vaccine

The combined vaccine against diphtheria, tetanus, pertussis, hepatitis B, poliomyelitis, and Haemophilus influenzae b (DTPa-HBV-IPV/Hib, Infanrix Hexa, GSK) has been used for childhood immunization in Australia according to a two-, four-, six-month schedule since 2009. We reviewed data available in the Australian National Notifiable Diseases Surveillance System, annual vaccination coverage reports, the Database of Adverse Event Notifications, and peer-reviewed literature to assess vaccine coverage rates, incidence of all six vaccine preventable diseases, and the safety profile of DTPa-HBV-IPV/Hib vaccine in Australian infants over a period of ten years of exclusive use. Between 2009 and 2018 vaccine coverage for infants aged 12 months increased from 91.7% to 94.0% and from 84.9% to 92.6% for all and for Indigenous infants, respectively. Over the same time period, there were no reports of poliomyelitis, diphtheria or tetanus in infants <12 months of age. The incidence of hepatitis B among Australian infants <12 months of age remains 10 to 20-fold lower than the national average. Control of Haemophilus influenzae b (Hib) and pertussis disease has continued to be challenging. Timely administration of the primary series, as well as increasing coverage rates, particularly among Indigenous children, has contributed to improvements in Hib and pertussis disease control. The incorporation of additional strategies such as adjustment of the first vaccination encounter to six weeks of age, parental cocooning, and most recently maternal vaccination has further reduced the burden of pertussis, particularly during the first six months of life. The frequency of the ten most common adverse events related to the DTPa-HBV-IPV/Hib vaccine demonstrates an acceptable safety profile. Data collected over ten years of consistent, exclusive use of the DTPa-HBV-IPV/Hib vaccine in Australia highlights combination vaccination as a cornerstone in maintaining infant health.

Immunogenicity and safety of a combined DTPa-IPV/Hib vaccine administered as a three-dose primary vaccination course and a booster dose in healthy children in Russia: a phase III, non-randomized, open-label study

We assessed the immunogenicity and safety of the combined diphtheria-tetanus-acellular pertussis-inactivated poliovirus/Haemophilus influenzae type b vaccine (DTPa-IPV/Hib) in children in Russian Federation aiming to support the registration of the vaccine in Russia. In this phase 3, non-randomized, open-label study (NCT02858440), healthy children received three primary doses at 3, 4.5, and 6 months of age (N = 235) and a booster dose at 18 months of age (N = 225). Seroprotection rates against diphtheria, tetanus, Hib, and poliovirus 1–3, seropositivity rates against pertussis antigens, and antibody geometric mean concentrations/titers for all antigens were evaluated one month post-primary and post-booster vaccinations. Solicited local and general adverse events (AEs) were collected during a 4-day period and unsolicited AEs during a 31-day period post-vaccination. Serious AEs were recorded throughout the study. At post-primary vaccination, all infants were seroprotected against diphtheria, tetanus, and poliovirus 1 and 2, 99.3% against poliovirus 3, and 98.4% against Hib. At least 98.9% of participants were seropositive for the three pertussis antigens. At post-booster vaccination, all toddlers were seroprotected/seropositive against all vaccine components. The most frequent local and general solicited AEs were redness, reported for 52.6% and 44.9% of children, and irritability, reported for 64.7% and 39.1% of children, post-primary and post-booster vaccination, respectively. Unsolicited AEs were reported for 20.4% (post-primary) and 5.8% of children (post-booster vaccination). Most AEs were mild or moderate in intensity. Six serious AEs were reported in three (0.4%) children; none were fatal or assessed as vaccination-related. DTPa-IPV/Hib proved immunogenic and well tolerated in the Russian pediatric population.

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.

Hexavalent vaccines in preterm infants: an update by Italian Society of Pediatric Allergy and Immunology jointly with the Italian Society of Neonatology

Hexavalent vaccines, protecting against six diseases (diphtheria, tetanus, pertussis [DTaP], poliovirus, hepatitis B virus [HBV], and Haemophilus influenzae type b [Hib], are routinely the standard of care in Europe. The use of combined vaccines allows the reduction of number of injections and side effects, the reduction of costs, and the increase in adherence of the family to the vaccination schedule both in terms of the number of doses and timing. The safety profile, efficacy and effectiveness of hexavalent vaccines have been extensively documented in infants and children born at term, and data are accumulating in preterm infants. Hexavalent vaccines are particularly important for preterm infants, who are at increased risk for severe forms of vaccine preventable diseases. However, immunization delay has been commonly reported in this age group. All the three hexavalent vaccines currently marketed in Italy can be used in preterm infants, and recent data confirm that hexavalent vaccines have a similar or lower incidence of adverse events in preterm compared to full-term infants; this is likely due to a weaker immune system response and reduced ability to induce an inflammatory response in preterm infants. Apnoea episodes are the adverse events that can occur in the most severe preterm infants and / or with history of respiratory distress. The risk of apnoea after vaccination seems to be related to a lower gestational age and a lower birth weight, supporting the hypothesis that it represents an unspecific response of the preterm infant to different procedures. High seroprotection rates have been reported in preterm infants vaccinated with hexavalent vaccine. However, a lower gestational age seems to be associated with lower antibody titres against some vaccine antigens (e.g. HBV, Hib, poliovirus serotype 1, and pertussis), regardless of the type of hexavalent vaccine used. Waiting for large effectiveness studies, hexavalent vaccines should be administered in preterm infants according to the same schedule recommended for infants born at term, considering their chronological age and providing an adequate monitoring for cardio-respiratory events in the 48–72 h after vaccination, especially for infants at risk of recurrence of apnoea.

Integration of hexavalent diphtheria, tetanus, acellular pertussis, hepatitis B virus, inactivated poliomyelitis and Haemophilus influenzae type b conjugate vaccine within existing national recommendations following a birth dose of monovalent hepatitis B virus vaccine: results of a systematic review in the Asia Pacific region

Introduction: In Asia Pacific, most countries recommend a monovalent hepatitis B virus (HBV) vaccine dose at birth followed by primary vaccination series including three or four doses of combination vaccines against diphtheria, tetanus, and pertussis, with or without Haemophilus influenzae type b (Hib), HBV or poliomyelitis antigens. If hexavalent conjugate vaccines against diphtheria-tetanus-acellular pertussis-HBV-inactivated poliovirus-Hib (DTPa-HBV-IPV/Hib) replace the vaccines included in the primary vaccination series, co-administration of lower-valent vaccines would be avoided but infants would receive ≥4 doses of HBV-containing vaccines before the age of 2 years. Areas covered: We searched for clinical trials conducted in the South-East Asia and Western Pacific Regions (World Health Organization geographic definition), investigating vaccination regimens with >3 doses of HBV-containing vaccines in infants, including a monovalent HBV vaccine birth dose and ≥1 dose of GSK's hexavalent DTPa-HBV-IPV/Hib vaccine. Expert opinion: The six clinical trials included in this review showed that infants who received the monovalent HBV vaccine at birth and three or four doses of DTPa-HBV-IPV/Hib vaccine achieved protective immunogenic titers with a clinically acceptable safety profile. Our results support the integration of hexavalent DTPa-HBV-IPV/Hib vaccine within existing national recommendations in the Asia Pacific region to reduce the number of injections during infancy.

Knowledge and practices regarding infant vaccination: results of a survey of French physicians

A prospective, observational, survey of pediatricians and general practitioners (GPs) was conducted to assess pediatric vaccination knowledge and practices. The survey was distributed by email to 1069 pediatricians and 1700 GPs and completed by 151 pediatricians (14.1%) and 201 GPs (11.8%). Knowledge of the vaccination calendar was very good (99% overall). Of the respondents, 98% were confident in vaccine efficacy. Eight-one percent of pediatricians and 62% of GPs agreed that recommended vaccinations should become obligatory; all prescribed hexavalent vaccines often or always. More pediatricians (88%) than GPs (75%) used anti-pyretics; the use of anesthetic cream/patches was similar in each group (79% and 75%, respectively). The ambience at vaccination was considered to be important by both groups, and was disturbed in 37% of cases. Seventy percent of pediatricians and 57% of GPs agreed that vaccine reconstitution (e.g., Hib pellet) is a complicating factor: overall, 28% reported occasionally omitting to reconstitute a pentavalent or hexavalent vaccine in error, and 60% reported having not fully reconstituted the vaccine. Almost all (93%) considered non-reconstitution as an important error.Conclusion: Overall, adherence to good vaccination practices was good, although errors in reconstitution were reported by physicians. These problems would be minimized by wider use of fully liquid vaccines. What is Known: • Pediatric vaccination schedules are crowded. • Good vaccination practices and the use of multivalent vaccines are essential to maintain good compliance to pediatric vaccination recommendations. What is New: • Overall good compliance to good vaccination practices by both pediatricians and GPs in France. • Omission of pentavalent or hexavalent vaccine reconstitution of Hib pellet and incomplete reconstitution reported by pediatricians/GPs. Awareness of pediatricians/GPs that omission and incomplete reconstitution are important errors.

Antibody persistence in pre-school children after hexavalent vaccine infant primary and booster administration

Objective: Antibody persistence evaluation for all antigens of a fully liquid DTaP-IPV-HB-PRP~T vaccine at 3.5 and 4.5 y of age following different primary series and booster schedules in South Africa and Latin America.

Methods: Participants had completed one of two previous studies (Study 1-South Africa; Study 2-Latin America). In Study 1, participants who had not received HB vaccine at birth received a 6–10-14 week primary series of DTaP-IPV-HB-PRP~T or DTwP/PRP~T-Hib+HB+OPV and a third group who had received HB vaccine at birth received a 6–10-14 week primary series of DTaP-IPV-HB-PRP~T; all received a booster (15–18 months) of the primary series vaccine(s) except for HB in the DTwP/PRP~T-Hib group. In Study 2, participants received HB vaccine at birth, a 2–4-6 month primary series of DTaP-IPV-HB-PRP~T or DTaP-HB-IPV//PRP~T, and a DTaP-IPV-HB-PRP~T or DTaP-HB-IPV//PRP~T booster (12–24 months). Participants were followed up at 3.5 and 4.5 y of age for antibody persistence.

Results: Approximately 80% of eligible participants were assessed. In Study 1, a birth dose of HB increased anti-HBs persistence (≥10 mIU/mL) following DTaP-IPV-HB-PRP~T primary and booster vaccination from 76.3% to 96.1% at 3.5 y of age and from 73.3% to 96.1% at 4.5 y of age; in Study 2, anti-HBs persistence was high and similar in each group. For the other antigens, there were no differences between groups or studies at 3.5 or 4.5 y.

Conclusion: Good persistence of antibodies to each antigen in the DTaP-IPV-HB-PRP~T vaccine up to pre-school age, irrespective of the vaccination schedule during the first 2 y of life.

Persistence of hepatitis B immune memory until 9-10 years of age following hepatitis B vaccination at birth and DTaP-IPV-HB-PRP∼T vaccination at 2, 4 and 6 months

OBJECTIVE

To evaluate the long-term persistence of anti-hepatitis B surface (HBs) antibodies and the response to a HB challenge re-vaccination in children who had received a primary series of DTaP-IPV-HB-PRP∼T (Hexaxim™) or DTaP-IPV-HB/PRP∼T (Infanrix hexa™).

METHODS

Two cohorts of participants who had previously received HB vaccine at birth followed by either DTaP-IPV-HB-PRP∼T or DTaP-IPV-HB/PRP∼T co-administered with PCV7 at 2, 4, 6 months of age in a randomized, Phase III, observer-blind study in Thailand, were followed up for anti-HBs antibodies (geometric mean concentrations [GMCs] and seroprotection [SP] rate [% of participants with a titer ≥10 mIU/mL]) at 12-18 months of age and 9-10 years of age. A monovalent HB challenge re-vaccination was administered at 9-10 years of age and the anamnestic response was evaluated.

RESULTS

Anti-HBs GMCs and SP rates in the DTaP-IPV-HB-PRP∼T and DTaP-IPV-HB/PRP∼T groups were high and similar post-primary vaccination series (2477 mIU/mL and 99.5% and 2442 mIU/mL and 99.5%, respectively) and declined to a similar extent in each group at 12-18 months (154.5 mIU/mL and 90.8% and 162.3 mIU/mL and 96.5%, respectively). Antibody levels further declined at 9-10 years of age (13.3 mIU/mL and 49.3% and 8.0 mIU/mL and 42.9%) and a strong anamnestic response occurred in each group post-HB challenge re-vaccination (92.8% and 98.7%, respectively).

CONCLUSION

The kinetics of long-term anti-HBs antibody persistence were similar following a primary series of DTaP-IPV-HB-PRP∼T or DTaP-IPV-HB/PRP∼T. The response to a subsequent HB challenge re-vaccination was strong and similar in each group, demonstrating persisting immune memory.

Immunogenicity and safety of primary and booster vaccination with 2 investigational formulations of diphtheria, tetanus and Haemophilus influenzae type b antigens in a hexavalent DTPa-HBV-IPV/Hib combination vaccine in comparison with the licensed Infanrix hexa

Safety and immunogenicity of 2 investigational formulations of diphtheria, tetanus and Haemophilus influenzae type b antigens of the combined diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliomyelitis-Hib vaccine (DTPa-HBV-IPV/Hib) were evaluated in a Primary (NCT01248884) and a Booster vaccination (NCT01453998) study.

In the Primary study, 721 healthy infants (randomized 1:1:1) received 3 doses of DTPa-HBV-IPV/Hib formulation A (D_AT_APa-HBV-IPV/Hib), or B (D_BT_BPa-HBV-IPV/Hib) or the licensed DTPa-HBV-IPV/Hib vaccine (Infanrix hexa, GSK; control group) at 2, 3, 4 months of age. Infants were planned to receive a booster dose at 12–15 months of age with the same formulation received in the Primary study; however, following high incidence of fever associated with the investigational formulations in the Primary study, the Booster study protocol was amended and all infants yet to receive a booster dose (N = 385) received the licensed vaccine.

In the Primary study, non-inferiority of 3-dose vaccination with investigational formulations compared with the licensed vaccine was not demonstrated due to anti-pertactin failing to meet the non-inferiority criterion. Post-primary vaccination, most infants had seroprotective levels of anti-diphtheria (100% of infants), anti-tetanus antigens (100%), against hepatitis B (≥ 97.5% across groups), polyribosyl-ribitol-phosphate (≥ 88.0%) and poliovirus types 1–3 (≥ 90.5%). Seropositivity rates for each pertussis antigen were 100% in all groups.

Higher incidence of fever (> 38°C) was reported in infants receiving the investigational formulations (Primary study: 75.0% [A] and 72.1% [B] vs 58.8% [control]; Booster study, before amendment: 49.4% and 46.6% vs 37.4%, respectively).

The development of the investigational formulations was not further pursued.

New perspectives for hexavalent vaccines

With the increase in the number of routine vaccinations the development of pentavalent and hexavalent combination vaccines fitting the routine vaccination schedules became a necessity. In this respect, Europe has taken the lead in comparison with other world regions, and routine vaccination with pentavalent and hexavalent combinations including DTPa, Hib, HepB and IPV has been on European vaccination programs for >15years. Since the marketing authorization of Hexavac® and Infanrix Hexa® in 2000, immunization schedules in most European countries have included hexavalent vaccines. In the last years, two new hexavalent vaccines have been licensed and commercialized worldwide. This paper presents a review of the pharmaceutical profiles of the three hexavalent vaccines currently available. In addition, we aim to review safety, co-administration, tolerability and other practical concerns of their use.

Immunogenicity and safety of 3-dose primary vaccination with combined DTPa-HBV-IPV/Hib in Indian infants

Multivalent combination vaccines have reduced the number of injections and therefore improved vaccine acceptance, timeliness of administration and global coverage. The hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus/Haemophilus influenzae type b (DTPa-HBV-IPV/Hib; Infanrix hexa™) vaccine, administered according to various schedules, is widely used for the primary vaccination of infants worldwide. In the current publication, we are presenting the immunogenicity and safety of 3 doses of DTPa-HBV-IPV/Hib vaccine when administered to Indian infants. 224 healthy infants (mean age 6.8 weeks) were vaccinated at 6-10-14 weeks (W) of age (n = 112) or 2-4-6 months (M) of age (n = 112). One month after the third vaccine dose, the seroprotection/seropositivity status against diphtheria, pertussis, tetanus, polio, hepatitis B and Hib antigens ranged from 98.6% to 100% in both groups. The vaccine response rate to the pertussis antigens ranged from 97% to 100%. Pain (6-10-14W group: 25.2%; 2-4-6M group: 13.4%) and fever (15.3% and; 15.2%, respectively) were the most frequently reported solicited local and general symptoms. Unsolicited adverse events were reported for 35.7% (6-10-14W group) and 22.3% (2-4-6M group) of subjects. No vaccine related serious adverse events were reported. In conclusion, the hexavalent DTPa-HBV-IPV/Hib vaccine was immunogenic and well tolerated, irrespective of the dosing schedule.

DTaP5-IPV-Hib-HepB, a hexavalent vaccine for infants and toddlers

INTRODUCTION

Combination vaccines reduce the 'shot burden' and simplify the childhood immunization schedule. Only 5-valent DTaP-based vaccines are licensed in the U.S. Areas covered: A new combination vaccine - DTaP5-IPV-Hib-HepB - is described, which induces antibody responses in infants (given in different schedules, including a 2, 4, and 6-month schedule) that are similar to the respective component vaccines. The vaccine appears to be safe and would be expected to protect against six diseases: diphtheria, tetanus, pertussis, hepatitis B, H influenzae type b, and polio. Administration is associated with higher rates of mild fever, but without significant safety signals. Expert commentary: Incorporation of this hexavalent vaccine into the U.S. schedule could improve coverage rates and timeliness, and addition to the E.U. market would add depth to the available repertoire of combination vaccines.

Lasting immune memory against hepatitis B in 12-13-year-old adolescents previously vaccinated with 4 doses of hexavalent DTPa-HBV-IPV/Hib vaccine in infancy

BACKGROUND

Vaccinating infants against hepatitis B virus (HBV) is the most effective way of preventing the disease. However, since HBV exposure can increase during adolescence, it is essential that antibody persistence is maintained. We evaluated the antibody persistence and immune memory against hepatitis B, in 12-13 y olds who had received complete primary + booster vaccination with diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus/Haemophilus influenza type b (DTPa-HBV-IPV/Hib) vaccine in infancy.

METHODS

Open phase-IV study conducted at 12 centers in Germany [NCT02052661]. Adolescents aged 12-13 y, vaccinated with 4 doses of DTPa-HBV-IPV/Hib (Infanrix hexa™, GSK Vaccines) in infancy, received a single challenge dose of monovalent pediatric hepatitis B vaccine (Engerix™-B Kinder; GSK Vaccines). Blood samples were taken before and 1-month post-challenge to measure anti-hepatitis B (anti-HBs) antibodies using a chemiluminescence immunoassay (seroprotection cut-off: ≥10 mIU/ml). Post-challenge adverse events (AEs) were monitored.

RESULTS

300 subjects were vaccinated; of 293 subjects in the ATP immunogenicity cohort, 60.5% had pre-challenge anti-HBs antibodies ≥10 mIU/ml, which rose to 97.6% post-challenge (≥100 mIU/ml in 94.1%). An anamnestic response was seen in 96.5% subjects. A 150-fold increase in antibody geometric mean concentrations was observed (22.4 to 3502.6 mIU/ml). Pain (44%) and fatigue (24.3%) were the most frequent solicited local and general AEs, respectively; 14.7% subjects reported unsolicited symptoms during the 31-day post-vaccination period. Two vaccine-unrelated serious AEs occurred.

CONCLUSION

Vaccination with DTPa-HBV-IPV/Hib in infancy induces sustained seroprotection and immune memory against HBV, as shown by the strong anamnestic response to the hepatitis B vaccine challenge in 12-13 year-old adolescents.

Vaccine Timeliness: A Cost Analysis of the Potential Implications of Delayed Pertussis Vaccination in the US

BACKGROUND

Pertussis infection remains an important public health problem, particularly in infants. Despite high coverage, pertussis vaccination delays can leave infants at a vulnerable age with less protection than anticipated.

METHODS

Current diphtheria-tetanus-pertussis (DTaP) vaccination timeliness for the first 3 doses in the US was estimated using National Immunization Survey data. A Markov model estimated the potential impact on outcomes and costs of a hypothetical situation of vaccination at exactly 60, 120 and 180 days, compared with current timeliness. Incidence and unit cost data came from published sources. Age-specific incidence (for month of life) of pertussis and the associated probabilities of hospitalization and death for the US, during 2000-2007, were taken from a recently published US DTaP vaccination cost-effectiveness study. The cost analysis was conducted from the healthcare system's perspective over a 1-year time horizon. A regression analysis was conducted to explore the factors associated with vaccination delay.

RESULTS

Current DTaP vaccination was estimated to be delayed by 16, 27 and 44 days, for the first, second and third doses, respectively, relative to vaccination at exactly 60, 120 and 180 days. The model estimated that vaccination at exactly age 60, 120 and 180 days could prevent approximately 278 pertussis cases, 103 hospitalizations and 1 death in infants aged <1 year in the US, gaining approximately 38 quality-adjusted life years and saving approximately $1.03 million in healthcare costs.

CONCLUSIONS

Timely administration of infant pertussis vaccine doses could potentially reduce subsequent pertussis cases, hospitalizations, deaths and medical costs in infants aged <1 year in the US.

Immunological persistence in 5 y olds previously vaccinated with hexavalent DTPa-HBV-IPV/Hib at 3, 5, and 11 months of age

The combined diphtheria-tetanus-acellular pertussis-hepatitis B-poliomyelitis/Haemophilus influenza vaccine (DTPa-HBV-IPV/Hib: Infanrix™ hexa, GlaxoSmithKline Vaccines) is used for primary vaccination of infants in a range of schedules world-wide. Antibody persistence after 4 DTPa-HBV-IPV/Hib doses in the first 2 y of life has been documented, but long-term persistence data following the 3, 5, 11–12 months (3–5–11) infant vaccination schedule, employed for example in Nordic countries, are limited. We assessed antibody persistence in 57 5-year-old children who had received either DTPa-HBV-IPV/Hib or DTPa-IPV/Hib (Infanrix™-IPV/Hib, GlaxoSmithKline Vaccines) in the 3–5–11 schedule. Among DTPa-HBV-IPV/Hib recipients, 7/12 retained seroprotective antibody concentrations for diphtheria, 10/12 for tetanus, 5/12 for hepatitis and 10/12 for Hib. Detectable antibodies were observed for 0/12 children for pertussis toxin (PT), 12/12 for filamentous haemagglutinin (FHA) and 8/12 for pertactin (PRN). Among DTPa-IPV/Hib recipients, 28/45 retained seroprotective anti-diphtheria concentrations, 34/44 for tetanus and 40/45 for Hib. Detectable antibodies were observed for 9/45 children for PT, 41/45 for FHA and 34/45 for PRN. Antibody persistence in DTPa-HBV-IPV/Hib and DTPa-IPV/Hib-vaccinees appeared similar in 5 y olds to that previously observed in children of a similar age who had received 4 prior doses of DTPa-HBV-IPV/Hib (or DTPa-IPV/Hib). As in subjects primed with 4 prior doses, we observed that antibodies markedly declined by 5 y of age, calling for the administration of a pre-school booster dose in order to ensure continued protection against pertussis.

Immunogenicity, Safety, and Tolerability of a Hexavalent Vaccine in Infants

BACKGROUND

DTaP5-IPV-Hib-HepB is a fully liquid investigational hexavalent vaccine directed against 6 diseases.

METHODS

This multicenter, open-label, comparator-controlled, phase III study randomly assigned healthy infants 2-to-1 as follows: group 1 received DTaP5-IPV-Hib-HepB, PCV13, and RV5 at 2, 4, and 6 months of age followed by DTaP5, Hib-OMP, and PCV13 at 15 months of age; group 2 received DTaP5-IPV/Hib, PCV13, and RV5 at 2, 4, and 6 months of age, with HepB at 2 and 6 months of age, followed by DTaP5, Hib-TT, and PCV13 at 15 months of age.

RESULTS

Overall, 981 participants were vaccinated in group 1 and 484 in group 2. Immune responses in group 1 to all antigens contained in DTaP5-IPV-Hib-HepB 1 month after dose 3 and for concomitant rotavirus vaccine were noninferior to those in group 2, with the exception of antipertussis filamentous hemagglutinin (FHA) geometric mean concentrations (GMCs). Vaccine response rates for FHA were noninferior to control. After the toddler dose, group 1 immune responses were noninferior to group 2 for all pertussis antigens. Solicited adverse event rates after any dose were similar in both groups, with the exceptions of increased injection-site erythema, increased fever, and decreased appetite in group 1. Fever was not associated with hospitalization or seizures.

CONCLUSIONS

The safety and immunogenicity of DTaP5-IPV-Hib-HepB are comparable with the analogous licensed component vaccines. Decreased FHA GMCs and increased injection-site reactions and fever are unlikely to be clinically significant. DTaP5-IPV-Hib-HepB provides a new combination vaccine option aligned with the recommended US infant immunization schedule.

Lasting immune memory against hepatitis B following challenge 10-11 years after primary vaccination with either three doses of hexavalent DTPa-HBV-IPV/Hib or monovalent hepatitis B vaccine at 3, 5 and 11-12 months of age

BACKGROUND

The combined hexavalent diphtheria-tetanus-pertussis-hepatitis B-inactivated poliomyelitis - Haemophilus influenzae type b conjugate vaccine (Infanrix hexa™; DTPa-HBV-IPV/Hib: GlaxoSmithKline Vaccines) induces robust responses to the HBV component when administered at 3, 5 and 11-12 months of age. We assessed long term HBV antibody persistence 10-11 years after primary vaccination in infancy.

METHODS

Antibody persistence and immune memory were assessed post-primary vaccination at 3, 5, 11-12 months with DTPa-HBV-IPV/Hib, or monovalent HBV vaccine (Engerix™ B, GlaxoSmithKline Vaccines) co-administered with DTPa-IPV/Hib (Infanrix™-IPV/Hib, GlaxoSmithKline Vaccines) in 185 children aged 11-12 years. Blood samples were collected before and 1 month after a challenge dose of Engerix™ B (10μg dose).

RESULTS

10-11 years after primary vaccination the percentage of subjects with persisting anti-HBs antibody concentrations ≥10mIU/ml was 48.4% in the DTPa-HBV-IPV/Hib group and 58.4% in the DTPa-IPV/Hib+HBV group. After the HBV challenge dose, the percentage with anti-HBs ≥100mIU/ml increased from 14.7% to 93.6% in the DTPa-HBV-IPV/Hib group and 19.1% to 94.4% in the DTPa-IPV/Hib+HBV group. Anti-HBs GMCs increased by at least 187-fold in each group. An anamnestic response (≥4-fold increase in initially seropositive or anti-HBs concentration ≥10mIU/ml in initially seronegative subjects) was observed in 96.8% and 96.6% of subjects in the DTPa-HBV-IPV/Hib and DTPa-IPV/Hib+HBV groups, respectively. No serious adverse events occurred that were considered related to challenge vaccination.

CONCLUSION

Administration of HBV as part of a combination vaccine or as a monovalent vaccine induced long lasting immune memory against HBV in children primed at 3, 5 and 11 months of age. Antibody persistence and immune memory were similar, suggesting that protection afforded by DTPa-HBV-IPV/Hib and monovalent HBV vaccines, is likely to be of similar duration. The administration of HBV challenge dose 10-11 years after the 3, 5, 11-12 months primary schedule induced strong anamnestic responses and was well tolerated. This study is registered at www.clinicaltrials.govNCT01138098.

Immune memory to hepatitis B persists in children aged 7-8 years, who were vaccinated in infancy with 4 doses of hexavalent DTPa-HBV-IPV/Hib (Infanrix™ hexa) vaccine

Protection against hepatitis B disease relies on either protective serum antibodies or on the ability of the immune system to mount an anamnestic response when confronted with the hepatitis B virus (HBV). This open multicenter study (EUDRACT: 2010-022538-10) measured antibodies to HBV surface antigen (anti-HBs) in 7-8-year-old children who had received 4 doses of hexavalent diphtheria-tetanus-acellular pertussis-HBV-inactivated poliovirus-Hemophilus influenzae type b conjugate vaccine (DTPa-HBV-IPV/Hib: Infanrix™ hexa; GlaxoSmithKline Vaccines) in the first 2 years of life through routine vaccine services in Germany. The ability of these children to mount an anamnestic response to a challenge dose of monovalent HBV vaccine (Engerix™ B Kinder; GlaxoSmithKline Vaccines) was also assessed. Before the challenge dose, 78.5% of children had anti-HBs levels ≥6.2 mIU/mL (seropositive) and 72.2% had anti-HBs levels ≥10 mIU/mL (seroprotected). Post-challenge, 98.9% had anti-HBs levels ≥10 mIU/mL and 95.8% had anti-HBs ≥100 mIU/mL. An anamnestic response to the challenge was observed in 96.6% of all subjects. The challenge dose was well tolerated, with a reactogenicity and safety profile consistent with published data. DTPa-HBV-IPV/Hib induces long-lasting immune memory to HBV that appears very similar to that induced by monovalent HBV vaccines. Protection against hepatitis B may be conferred through immune memory in subjects who responded to primary vaccination, even when they subsequently lose detectable levels of circulating anti-HBs antibodies.

Vaccine chronicle in Japan

The concept of immunization was started in Japan in 1849 when Jenner's cowpox vaccine seed was introduced, and the current immunization law was stipulated in 1948. There have been two turning points for amendments to the immunization law: the compensation remedy for vaccine-associated adverse events in 1976, and the concept of private vaccination in 1994. In 1992, the regional Court of Tokyo, not the Supreme Court, decided the governmental responsibility on vaccine-associated adverse events, which caused the stagnation of vaccine development. In 2010, many universal vaccines became available as the recommended vaccines, but several vaccines, including mumps, zoster, hepatitis B, and rota vaccines, are still voluntary vaccines, not universal routine applications. In this report, immunization strategies and vaccine development are reviewed for each vaccine item and future vaccine concerns are discussed.

Sensorimotor polyneuropathy after hexavalent vaccination

New vaccines in infants are generally well tolerated and serious adverse events are rare. We present a patient who developed severe sensorimotor polyneuropathy 2 weeks after the first immunization with hexavalent routine vaccine (INFANRIX hexa). Through intense physiotherapy the infant made a complete recovery.

Combined hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus-Haemophilus influenzae type B vaccine; Infanrix™ hexa: twelve years of experience in Italy

Infant vaccination using 2-dose priming at 3 and 5 mo of age with a booster at 11–12 mo of age was pioneered in Italy. The 3-5-11 schedule is now used in a growing number of European countries. Infanrix™ hexa (DTPa-HBV-IPV/Hib, GlaxoSmithKline Vaccines) was first licensed for use in 2000 and has been the only pediatric hexavalent vaccine available since 2005. We reviewed available clinical trial data describing the immunogenicity of DTPa-HBV-IPV/Hib when administered at 3, 5, and 11 mo of age, and conducted an analysis of safety using global and Italian post-marketing surveillance data. In Italy, DTPa-HBV-IPV/Hib has a demonstrated safety record extending over a decade of use, it has been associated with record levels of vaccine coverage, and with sustained disease control in vaccinated cohorts. Hexavalent vaccines will continue to contribute to high vaccine coverage in Italy and across Europe.

A randomized, controlled trial to assess the immunogenicity and safety of a heptavalent diphtheria, tetanus, pertussis, hepatitis B, poliomyelitis, hib and meningococcal serogroup C combination vaccine administered at 2, 3, 4 and 12-18 months of age

BACKGROUND

Combination vaccines offer protection against multiple diseases with fewer injections. This study evaluated the immunogenicity and safety of an investigational diphtheria, tetanus, acellular pertussis, hepatitis B, poliomyelitis, Haemophilus influenzae type b (Hib) and meningococcal serogroup C (MenC) heptavalent combination vaccine (heptavalent vaccine) given as 4 doses at 2, 3, 4 and 12-18 months of age.

METHODS

In this randomized, open, phase II study (NCT00970307/NCT01171989) conducted in Poland, 421 infants were enrolled to receive the heptavalent vaccine or licensed comparator vaccines. Immunogenicity against study vaccine antigens was measured prior to and 1 month after primary and booster vaccinations. Safety and reactogenicity of the vaccines were also evaluated.

RESULTS

The primary noninferiority objectives of the MenC and Hib immune responses induced by the heptavalent vaccine versus comparator vaccines were reached after primary vaccination, but no statistical conclusion could be drawn after booster dose. One month after primary and booster vaccinations, ≥98.4% of the heptavalent vaccine recipients were seroprotected for MenC and Hib. Exploratory analyses indicated that the heptavalent vaccine induced higher postprimary vaccination antibody geometric mean concentrations against Hib, but lower postprimary and postbooster vaccinations geometric mean titers against MenC compared with the relevant comparator vaccines. The reactogenicity profiles of the vaccines were acceptable, although 1 infant vaccinated with the heptavalent vaccine experienced a serious adverse event (thrombocytopenia) considered possibly related to vaccination.

CONCLUSIONS

The heptavalent vaccine was immunogenic and had a clinically acceptable safety profile when administered to infants and toddlers.

A combined Haemophilus influenzae type B Neisseria meningitidis serogroup C tetanus toxoid conjugate vaccine is immunogenic and well-tolerated when coadministered with diphtheria, tetanus, acellular pertussis hepatitis B-inactivated poliovirus at 3, 5 and 11 months of age: results of an open, randomized, controlled study

BACKGROUND

This study evaluated the immunogenicity, reactogenicity and safety of the combined Haemophilus influenzae type B Neisseria meningitidis serogroup C tetanus toxoid conjugate vaccine (Hib-MenC-TT) coadministered with diphtheria, tetanus, acellular pertussis hepatitis B-inactivated poliovirus (DTPa-HBV-IPV) as 2 primary and 1 booster doses at 3, 5 and 11 months of age.

METHODS

In this phase III open study (NCT00327184), 709 infants were randomized in 2 parallel groups (1:1) to receive either Hib-MenC-TT coadministered with DTPa-HBV-IPV or control vaccines (MenC-TT coadministered with DTPa-HBV-IPV/Hib). Serum bactericidal activity for MenC (rSBA-MenC) and antibody concentrations against polyribosylribitol phosphate from Hib (anti-PRP) and hepatitis B (anti-HBs) were measured at 1 month after dose 2, before booster and 1 month after booster dose. Solicited (local/general) and unsolicited symptoms were assessed up to 4 and 31 days, respectively, after each vaccination. Serious adverse events were recorded throughout the study.

RESULTS

One month after dose 2, high percentages of infants in both groups had rSBA-MenC titers ≥ 8 (≥ 99.1%), anti-PRP concentrations ≥ 0.15 μg/mL (≥ 96.5%) and anti-HBs concentrations ≥ 10 mIU/mL (≥ 95.3%), which persisted up to the booster vaccination (≥ 94.5%, ≥ 86.1%, ≥ 94.2%) and increased again after the booster dose (100%, 100%, ≥ 99%). Exploratory analyses indicated that rSBA-MenC geometric mean titers were lower and anti-PRP geometric mean concentrations were higher in the infants vaccinated with Hib-MenC-TT compared with the control vaccines at all time points. The safety profiles of the coadministered vaccines were similar in both groups.

CONCLUSIONS

The Hib-MenC-TT and DTPa-HBV-IPV vaccines are immunogenic with a clinically acceptable safety profile when coadministered as 2 primary doses during infancy and 1 booster dose at 11 months of age.

Persistence at one year of age of antigen-induced cellular immune responses in preterm infants vaccinated against whooping cough: comparison of three different vaccines and effect of a booster dose

Due to their high risk of developing severe Bordetella pertussis (Bp) infections, it is recommended to immunize preterm infants at their chronological age. However, little is known about the persistence of their specific immune responses, especially of the cellular responses recognized to play a role in protection. We compared here the cellular immune responses to two major antigens of Bp between three groups of one year-old children born prematurely, who received for their primary vaccination respectively the whole cell vaccine Tetracoq(®) (TC), the acellular vaccine Tetravac(®) (TV), or the acellular vaccine Infanrix-hexa(®) (IR). Whereas most children had still detectable IFN-γ responses at one year of age, they were lower in the IR-vaccinated children compared to the two other groups. In contrast, both the TV- and the IR-vaccinated children displayed higher Th2-type immune responses, resulting in higher antigen-specific IFN-γ/IL-5 ratios in TC- than in TV- or IR-vaccinated children. The IFN-γ/IL-5 ratio of mitogen-induced cytokines was also lower in IR- compared to TC- or TV-vaccinated children. No major differences in the immune responses were noted after the booster compared to the pre-booster responses for each vaccine. The IR-vaccinated children had a persistently low specific Th1-type immune response associated with high specific Th2-type immune responses, resulting in lower antigen-specific IFN-γ/IL-5 ratios compared to the two other groups. We conclude that antigen-specific cellular immune responses persisted in one year-old children born prematurely and vaccinated during infancy at their chronological age, that a booster dose did not significantly boost the cellular immune responses, and that the Th1/Th2 balance of the immune responses is modulated by the different vaccines.

DTPa-HBV-IPV/Hib vaccine (Infanrix hexa™): a guide to its use in infants

Infanrix hexa™, a diphtheria, tetanus, acellular pertussis, hepatitis B, inactivated poliomyelitis, and Haemophilus influenzae type b (Hib) conjugate vaccine, is indicated for primary and booster vaccination of infants. Available clinical data from more than a decade of experience with the vaccine indicate that primary and booster vaccination with Infanrix hexa™ is a safe and useful option for providing protection against the common childhood diseases of diphtheria, tetanus, poliomyelitis, pertussis, hepatitis B, and disease caused by Hib.

Immunogenicity and safety of 10-valent pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) co-administered with routine childhood vaccines in Taiwan

BACKGROUND/PURPOSE

The immunogenicity and safety of the 10-valent pneumococcal nontypeable Haemophilus influenzae (H. Influenzae) protein D conjugate vaccine (PHiD-CV), co-administered with routine childhood vaccines, were assessed in Taiwanese infants.

METHODS

In this open study, 230 healthy infants were primed with three doses of PHiD-CV (Synflorix) and diphtheria, tetanus, acellular pertussis, hepatitis B (HBV), inactivated poliomyelitis and Haemophilus influenzae type b (Hib) conjugate vaccine (DTPa-HBV-IPV/Hib vaccine) at 1.5, 3 and 6 months of age and two doses of oral human rotavirus vaccine at 1.5 and 3 months. Pneumococcal immune responses were assessed 1 month post-dose three, by 22F-inhibition ELISA and opsonophagocytic activity (OPA) assay. Local and general solicited/unsolicited symptoms and serious adverse events (SAEs) were recorded.

RESULTS

At least 95.4% of participants had an antibody concentration ≥ 0.2 μg/mL against each vaccine serotype. At least 96.1% of participants had an OPA titer ≥ 8 against each vaccine serotype except 6B (87.3%). All infants, but one, were seropositive for antibodies against nontypeable H. influenzae protein D. Immune responses to the co-administered vaccines were good and in line with previous reports. PHiD-CV was well tolerated, with low (≤ 6.3%) incidences of grade 3 solicited local symptoms. The frequencies of general symptoms were in line with other pneumococcal conjugate vaccine studies. There were no systematic increases in incidences of solicited general or local symptoms with successive doses. There were no reports of grade 3 fever (rectal temperature > 40 °C) or SAEs considered to be causally related to vaccination.

CONCLUSION

PHiD-CV co-administered with routine childhood vaccines within the first 6 months of life, was highly immunogenic, and well tolerated in Taiwanese infants.

Immunogenicity of Infanrix™ hexa administered at 3, 5 and 11 months of age

A pooled analysis of data from four vaccination studies conducted in Europe was undertaken to assess the immunogenicity of Infanrix™ hexa (DTPa-HBV-IPV/Hib, GlaxoSmithKline Biologicals) when administered in a total of 702 healthy infants at 3, 5 and 11-12 months of age. One month after dose 2, between 96.3% and 100% of subjects had seroprotective antibodies against diphtheria, tetanus, hepatitis B and poliovirus types 1, 2 and 3; 91.7% against Hib and ≥99.0% were seropositive for each pertussis antigen. One month after the third dose, 98.9-100% of subjects were seroprotected/seropositive for all vaccine antigens. Geometric mean antibody concentrations/titres for each vaccine antigen increased by 6.7-52.9 fold after the third vaccine dose. No serious adverse events in DTPa-HBV-IPV/Hib recipients were vaccine related. Infanrix™ hexa induces an adequate immune response after 2-dose primary plus booster doses when administered according to a 3, 5 and 11 months schedule.

The continuing role of Haemophilus influenzae type b carriage surveillance as a mechanism for early detection of invasive disease activity

Prior to the introduction of Haemophilus influenzae type b (Hib) conjugate vaccines, Hib was the leading cause of bacterial meningitis in children under five years of age worldwide. In countries that have adopted Hib vaccination schedules, invasive disease has reduced markedly. Oro-naso pharyngeal carriage is recognized as the most significant source of infection. Hib carriage is significantly associated with poverty, such as overcrowding, poor ventilation in houses, lack of running water, and high smoking rates. Additionally, many Indigenous minority groups report high rates of Hib carriage. A resurgence of Hib disease among Alaskan children in the 1990s, lead to a change in approach to eliminate Hib disease and carriage in high-risk populations. This new approach identifies strategies for eliminating Hib disease focusing on the reservoirs of colonization within families and communities. Monitoring Hib carriage continues to offer an early warning system, whereby intervention could prevent invasive disease resurgence.

Immunization of preterm infants with 10-valent pneumococcal conjugate vaccine

OBJECTIVE

The safety and immunogenicity of the 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) in preterm infants were assessed in this study.

METHODS

Three parallel groups of infants received 3-dose primary immunization with PHiD-CV at 2, 4, and 6 months of age and a booster dose at 16 to 18 months: preterm I (gestation period ≥ 27 and <31 weeks, N = 50); preterm II (≥31 and <37 weeks, N = 87); and term (≥37 weeks, N = 149). Solicited symptoms and adverse events were recorded. Immune responses to PHiD-CV and coadministered vaccine antigens were measured.

RESULTS

The incidence of solicited general symptoms was similar across groups, and the frequency of grade 3 general symptoms was low. Incidences of redness and swelling were generally lower in preterm infants. PHiD-CV was immunogenic for each of the 10 vaccine pneumococcal serotypes (postprimary, ≥92.7% of infants reached enzyme-linked immunosorbent assay antibody concentrations ≥ 0.2 μg/mL and postbooster, ≥97.6%) and for protein D, with a trend for lower postprimary geometric mean antibody concentrations and opsonophagocytic activity (OPA) titers in preterm infants for some pneumococcal serotypes. Postbooster, ≥91.9% of subjects in each group had an OPA titer ≥ 8 for each of the vaccine serotypes. Pneumococcal antibody concentrations and OPA titers after priming and booster vaccination were comparable between the 2 preterm groups.

CONCLUSIONS

PHiD-CV was well tolerated and immunogenic in preterm infants when given as a 3-dose primary vaccination, with robust enzyme-linked immunosorbent assay antibody and OPA booster responses in the second year of life.

Immunogenicity and safety of an investigational hexavalent diphtheria-tetanus-acellular pertussis-inactivated poliovirus-hepatitis B-Haemophilus influenzae B conjugate combined vaccine in healthy 2-, 4-, and 6-month-old Argentinean infants

BACKGROUND AND AIMS

Assessment of a new, fully liquid, investigational hexavalent DTaP-IPV-Hep B-PRP-T vaccine (Hexaxim, Sanofi Pasteur), containing the same active ingredients as Pentaxim (DTaP-IPV//PRT-T) and 10 μg Hansenula polymorpha-derived recombinant hepatitis B (Hep B) surface antigen, Sanofi Pasteur, in Argentinean infants.

METHODS

Infants born to Hep B surface antigen seronegative mothers were randomized to receive the DTaP-IPV-Hep B-PRP-T vaccine or Pentaxim and Engerix B Pediatrico (Hep B monovalent) vaccines at 2, 4, 6 months of age. Antibody titers were measured before and 1 month after 3-month primary vaccination. Noninferiority analyses were performed on seroprotection/seroconversion rates. Safety was evaluated descriptively up to 1 month after primary vaccination.

RESULTS

A total of 624 participants were enrolled, 312 participants were randomized to each group, and 604 participants completed the trial. The DTaP-IPV-Hep B-PRP-T vaccine was demonstrated as noninferior to the Pentaxim and Hep B monovalent vaccines with seroprotection/seroconversion rates 1 month postdose 3 for each valence. The anti-Hep B geometric mean titer 1-month postdose 3 for the investigational DTaP-IPV-Hep B-PRP-T primary series was similar to the monovalent Hep B control. The overall incidence of adverse events was similar among the 2 groups.

CONCLUSIONS

The new, fully liquid, investigational DTaP-IPV-Hep B-PRP-T vaccine (Hexaxim) is highly immunogenic and safe when compared with licensed comparators, warranting further development.

Switched memory B cells maintain specific memory independently of serum antibodies: the hepatitis B example

The immunogenicity of a vaccine is conventionally measured through the level of serum Abs early after immunization, but to ensure protection specific Abs should be maintained long after primary vaccination. For hepatitis B, protective levels often decline over time, but breakthrough infections do not seem to occur. The aim of this study was to demonstrate whether, after hepatitis B vaccination, B-cell memory persists even when serum Abs decline. We compared the frequency of anti-hepatitis-specific memory B cells that remain in the blood of 99 children five years after priming with Infanrix -hexa (GlaxoSmithKline) (n=34) or with Hexavac (Sanofi Pasteur MSD) (n=65). These two vaccines differ in their ability to generate protective levels of IgG. Children with serum Abs under the protective level, <10 mIU/mL, received a booster dose of hepatitis B vaccine, and memory B cells and serum Abs were measured 2 wk later. We found that specific memory B cells had a similar frequency in all children independently of primary vaccine. Booster injection resulted in the increase of memory B cell frequencies (from 11.3 in 10(6) cells to 28.2 in 10(6) cells, p<0.01) and serum Abs (geometric mean concentration, GMC from 2.9 to 284 mIU/mL), demonstrating that circulating memory B cells effectively respond to Ag challenge even when specific Abs fall under the protective threshold.

Immunogenicity and safety of an investigational fully liquid hexavalent combination vaccine versus licensed combination vaccines at 6, 10, and 14 weeks of age in healthy South African infants

BACKGROUND

Assessment of primary vaccination of a new fully liquid, hexavalent investigational DTaP-IPV-Hep B-PRP-T vaccine (Hexaxim) in South African infants.

METHODS

Infants were randomized to the following at 6, 10, and 14 weeks of age (Expanded Program on Immunization schedule): DTaP-IPV-Hep B-PRP-T (Group 1; N = 286); DTwP-Hib, hepatitis B, and OPV vaccines (Group 2; N = 286); or DTaP-IPV-Hep B-PRP-T vaccine with hepatitis B vaccine at birth (Group 3; N = 143). Antibody titers were measured before vaccination (pertussis toxoid, filamentous hemagglutinin) and postprimary vaccination (all valences). Noninferiority analyses were performed for Group 1 versus Group 2 for seroprotection rates. Safety was evaluated from parental reports.

RESULTS

Noninferiority (Group 1 minus Group 2) was demonstrated for anti-HBs, -PRP, -diphtheria, -tetanus, and -polio 1, 2, 3 (lower 95% confidence interval for the difference was -8.20 to 3.46). Anti-HBs antibody titers ≥10 mIU/mL and anti-PRP ≥0.15 μg/mL were ≥95.4% in each group. Seroprotection rates were also high for the other antigens. Seroconversion rates (4-fold increase from pre- to postvaccination) were 93.6%, 83.2%, and 95.1% in Groups 1, 2, and 3, respectively, for anti-pertussis toxoid and 93.1%, 57.7%, and 90.0% for anti-filamentous hemagglutinin. Anti-HBs GMTs were 330, 148, and 1913 mIU/mL for Groups 1, 2, and 3, respectively. Reactogenicity was similar in each group. Fever ≥39.0°C occurred in 1.7%, 0.4%, and 0.0% of infants in Groups 1, 2, and 3, respectively; no extensive limb swelling, hypotonic-hyporesponsive episodes, or vaccine-related serious adverse events were reported.

CONCLUSIONS

The new, fully liquid, investigational hexavalent vaccine in the Expanded Program on Immunization schedule, with/without hepatitis B at birth, is highly immunogenic and safe compared with control vaccines, warranting further development.

An investigational tetravalent meningococcal serogroups A, C, W-135 and Y-tetanus toxoid conjugate vaccine co-administered with Infanrix™ hexa is immunogenic, with an acceptable safety profile in 12-23-month-old children

Tetravalent meningococcal serogroups ACWY conjugate vaccines will provide an advantage to those at most risk of invasive meningococcal disease; namely young children. Co-administration of ACWY-TT with DTaP-HBV-IPV/Hib was assessed in a randomized trial in 793 children aged 12-23 months. Pre-specified criteria for non-inferiority of immunogenicity following co-administration versus separate ACWY-TT and DTaP-HBV-IPV/Hib administration were reached. One month post-vaccination, ≥ 97.3% of ACWY-TT vaccinees had rSBA titres ≥ 1:8 (all serogroups). Seroprotection/seropositivity rates against DTaP-HBV-IPV/Hib antigens were ≥ 98.2%. The safety profile of co-administration was similar to that of DTaP-HBV-IPV/Hib alone. ACWY-TT and DTaP-HBV-IPV/Hib co-administration during the second year would facilitate introduction of ACWY-TT into routine toddler vaccination schedules.

Immunogenicity and safety of an investigational combined haemophilus influenzae type B-Neisseria meningitidis serogroups C and Y-tetanus toxoid conjugate vaccine

BACKGROUND

Neisseria meningitidis serogroups B, C, and Y cause most meningococcal disease in industrialized countries. A Haemophilus influenzae type b-meningococcal serogroups C and Y-tetanus toxoid conjugate vaccine (HibMenCY-TT) was evaluated.

METHODS

A total of 1104 infants (randomized 3:1:1) were vaccinated at 2, 4, and 6 months with HibMenCY-TT, MenC-CRM197 + Hib-TT, or Hib-TT. At 12 to 15 months, HibMenCY-TT and MenC-CRM-primed children received HibMenCY-TT; Hib-TT-primed received N. meningitidis serogroup B Hib-outer membrane protein complex. Antibody concentrations and rabbit/human complement serum bactericidal antibody titers (rSBA/hSBA) were determined. Safety was monitored after each dose (diary cards for first 31 days) until 6 months postdose 4.

RESULTS

Postdose 3, rates of antipolyribosylribitol phosphate ≥ 1 μg/mL and rSBA-MenC ≥1:128 in HibMenCY-TT recipients were noninferior to licensed controls. Percentages reaching 0.15 μg/mL (1.0 μg/mL postdose 3) and antipolyribosylribitol phosphate GMC were significantly higher after HibMenCY-TT than Hib-TT postdose 2 and postdose 3. The GMC remained significantly higher before and after dose 4. Proportions of HibMenCY-TT recipients with rSBA ≥ 1:8 were 95.6% (MenC), 98.6% (MenY) postdose-2, ≥ 99% for MenC/Y postdose 3 and 4; hSBA ≥ 1:4 were 95.5% (MenC), 89.8% (MenY) postdose 2, >97% for MenC/Y postdose 3 and 4. HibMenCY-TT had a similar safety profile to control vaccines.

CONCLUSIONS

HibMenCY-TT induced noninferior Hib and MenC responses compared with monovalent Hib and MenC conjugates with a comparable safety profile. Bactericidal antibodies against MenC/Y were induced after 2 doses of HibMenCY-TT.

Combination vaccines

The combination of diphtheria, tetanus, and pertussis vaccines into a single product has been central to the protection of the pediatric population over the past 50 years. The addition of inactivated polio, Haemophilus influenzae, and hepatitis B vaccines into the combination has facilitated the introduction of these vaccines into recommended immunization schedules by reducing the number of injections required and has therefore increased immunization compliance. However, the development of these combinations encountered numerous challenges, including the reduced response to Haemophilus influenzae vaccine when given in combination; the need to consolidate the differences in the immunization schedule (hepatitis B); and the need to improve the safety profile of the diphtheria, tetanus, and pertussis combination. Here, we review these challenges and also discuss future prospects for combination vaccines.

The worldwide impact of vaccination on the control and protection of viral hepatitis B

Viral hepatitis B is a leading cause of acute and chronic liver disease worldwide, including cirrhosis and hepatocellular carcinoma. Vaccination is the most effective measure for controlling and preventing hepatitis B and its severe long-term sequelae. According to the World Health Organization (WHO), by the end of 2008 177 countries had introduced hepatitis B vaccination into their national routine neonatal, infant and/or adolescent immunisation programmes, and Italy was one of the first countries to implement a universal strategy of hepatitis B vaccination. The implementation of such vaccination programmes has globally resulted in a marked decrease in disease burden, in the carrier rate and in hepatitis B-related morbidity and mortality. Despite this success, work remains to be done to fully achieve the WHO goal of control of hepatitis B and HBV-related diseases on a global scale.