Report of the 2nd "French Clinical Vaccinology Meeting Jean-Gerard Guillet": immunization and respiratory diseases.

The 2nd French Clinical Vaccinology conference held on 20th April 2009 in Paris (France) was a unique opportunity to discuss basic and translational research in vaccinology and its implications for patients for respiratory diseases. This conference is organized by the Clinical Research Center Cochin-Pasteur, that has been involved for several years clinical research in vaccines. We report on here the key findings of the conference, especially the immunization of the chronic respiratory diseases, the clinical effectiveness of vaccines and the development of new vaccines in pulmonology.

Dynamic of pneumococcal nasopharyngeal carriage in children with acute otitis media following PCV7 introduction in France.

To determine whether the use of seven valent pneumococcal conjugate vaccine (PCV7) caused a shift in the Streptococcus pneumoniae serotypes distribution and whether it modified the resistance to antibiotics, 3291 nasopharyngeal swabs were obtained between 2001 and 2006, from children aged 6-24 months with acute otitis media. Following the implementation of PCV7, we observed a slight reduction in the overall pneumococcal carriage, a marked decrease of vaccine serotypes, an increase in non-vaccine serotypes carriage and a reduction in the carriage of penicillin non-susceptible strains. Most of the serotype 19A replacement was related to the clonal expansion of ST276 which was found to be the predominant ST among penicillin non-susceptible isolates.

Burden of paediatric invasive pneumococcal disease in Europe, 2005.

Within the European Union (EU), documenting the burden of invasive pneumococcal disease (IPD) in infants and children is important for coordinating effective pneumococcal immunization policies. Our objective was to document the burden of IPD in countries of the EU plus Switzerland and Norway. European affiliates of Wyeth Vaccines made available recent epidemiological data on IPD from local disease surveillance programmes, including unpublished sources. Recent literature and websites were also searched to provide as wide a representation as possible. This included OVID and abstracts from a number of international meetings, dating from the year 2000. The reported rates of paediatric IPD per 100000 (age) ranged from a low of 1.7 (<2 years) to 4.2 (2-15 years) in Sweden to a high of 93.5 to 174 (<2 years) to 56.2 (<5 years) in Spain. The percentage of circulating serotypes causing IPD that are covered by 7-valent pneumococcal conjugate vaccine (PCV) IPD serotype coverage ranged from 60% to 80% for European children aged <2 years. Under reporting, differences in reporting methods, antibiotic prescribing and disparities in blood-culturing practices may explain the differences in reported disease incidence. Because of the excellent clinical efficacy of the PCV against IPD, national pneumococcal vaccination programmes in Europe have the potential to prevent much morbidity and mortality.

Safety and immunogenicity of Haemophilus influenzae type b-tetanus toxoid conjugate, presented in a dual-chamber syringe with diphtheria-tetanus-pertussis and inactivated poliomyelitis combination vaccine.

The safety and immunogenicity of combining two established vaccines, polyribosyl ribitol phosphate conjugated to tetanus toxoid (PRP-T) (ActHIB, Pasteur Mérieux Connaught, Lyon, France) and diphtheria-tetanus-whole cell pertussis and inactivated poliovirus vaccine (DTP-IPV) (Tetracoq, Pasteur Mérieux Connaught, Lyon, France) were evaluated using a new dual-chamber syringe delivery system. Results were compared with those obtained when the two combination vaccines were either administered separately (two sites) or reconstituted manually and injected at a single site. A total of 487 2-month-old infants were enrolled in this study by 61 paediatricians in France. Infants were randomised to receive three immunisations of PRP-T and DTP-IPV at 2, 3 and 4 months of age, given either with the dual-chamber syringe (n = 213), as separate injections (n = 215), or as a single manually reconstituted injection (n = 59). Blood samples were taken prior to the first immunisation and 4 weeks after the third immunisation for the measurement of antibody titres. Infants were monitored by the parents for 3 days after each immunisation to detect local and systemic reactions. Local and systemic reactions occurring the 3 days following immmunisation were as expected for the combination vaccines used. Safety of the vaccination using the dual-chamber syringe was as good as, if not slightly better than, that for the two vaccines administered separately. After the first immunisation, pain and unusual crying were significantly more frequent in infants who received two injections, compared to those who were immunised with the dual-chamber syringe. Serological responses were good for all antigens in the three groups and there was no evidence for any immunological interference. Almost all subjects in each group achieved levels of antibodies considered to be protective for all antigens. There were no clinically relevant differences in antibody response between any of the groups. The dual-chamber and separate injection methods of vaccination were equivalent according to a pre-defined criterion (percentage of infants with anti-PRP antibody titres > or =1.0 microg/ml). Results from this study suggest that the two vaccines, PRP-T and DTP-IPV, may be safely and effectively administered in infants using the new dual-chamber syringe. This presentation provides an innovative strategy to combine different vaccines that are not yet available as a single formulation.

Safety and immunogenicity of MF59-adjuvanted influenza vaccine in the elderly.

Safety and immunogenicity of the influenza vaccine adjuvanted with MF59 (FLUAD) were compared to those of a non adjuvanted subunit vaccine in elderly subjects during three consecutive influenza seasons. Geometric mean titres and proportions of subjects with either a > or = four-fold increase in antibody titres or with an HI titre > or = 128 after immunisation were higher in FLUAD recipients. The adjuvant effect on the magnitude of the responses was most pronounced in subjects with pre-vaccination titres < or = 40. Although associated with more frequent mild local reactions, the adjuvanted vaccine was well tolerated. Thus, the addition of MF59 increased the immunogenicity of the subunit influenza vaccine in elderly persons with low pre-vaccination titres, who are at greatest risk of developing severe influenza disease and vaccine failure, without a clinically important increase in reactogenicity.

Bridging studies.

The duplication of usually large-scale efficacy trials to generalise the clinical database of a new vaccine to other populations can be avoided by bridging studies. Immunogenicity data can easily be used to extrapolate efficacy results when the immune response correlates with vaccine induced immunity. In the absence of such a correlate of protection, the bridging process will be more controversial. Previous experiences should be valuable in identifying the factors, either ethnic or vaccine-related that may have an influence on vaccine efficacy. The probability that such a factor is associated with a clinically significant difference in efficacy is critical to the decision to conduct a bridging study. Bridging studies are designed to demonstrate equivalent immunogenicity i.e. exclude a clinically significant difference in the immune response between the population in whom efficacy was shown and the population to whom those efficacy results are extrapolated.

Immunogenicity and safety of a liquid combination of DTP-PRP-T [corrected] vs lyophilized PRP-T reconstituted with DTP.

The immunogenicity and safety of a combined diphtheria, tetanus, pertussis and Haemophilus influenzae type b-tetanus conjugate vaccine (DTP-PRP-T) was compared to the same combination obtained by the reconstitution of H. influenzae type b-tetanus conjugate vaccine lyophilized (PRP-T) with liquid diphtheria-tetanus-pertussis vaccine (DTP). Two hundred and sixty-two healthy infants were randomized to receive a intramuscular injection of 0.5 ml of one of the above combination vaccines at 2, 4 and 6 months of age, and a subgroup of 134 infants received a booster dose at 12 months. Serum antibody levels to each vaccine component were measured at ages 2, 6, 7, 12 and 13 months. Systemic and local reactions were assessed during the first 3 days after each injection by diary cards distributed to the parents. After the third dose and booster administered at 12 months of age, significant equivalence between the groups was observed, and the geometric mean titer of anti H. influenzae type b capsular polysaccharide (Hib-CP) antibodies were 5.9 and 32.6 micrograms ml-1 for the liquid combination group and 5.8 and 19.4 for the lyophilized group, respectively. After the third dose, anti-Hib-PC antibody levels of > or = 1.0 microgram ml-1 and 0.15 microgram ml-1 were seen in 94% and 100%, respectively, of the liquid combination group and 90 and 99%, respectively of the lyophilized group. After the booster dose, levels of > or = 1.0 microgram ml-1 were observed in 100% and 93.5% of the liquid combination group and the lyophilized combination group, respectively. Systemic and local reactions to the vaccination were generally mild and did not differ significantly between the groups. We conclude that the liquid combination of DTP-PRP-T is safe and at least as immunogenic as the lyophilized preparation. This liquid preparation, like other combined vaccines may be helpful for planning vaccination programs with a reduced number of injections.

Factors associated with superior antibody responses to a single dose of Haemophilus influenzae type b-tetanus toxoid conjugate vaccine administered to Chilean infants at 2 months of age.

The anticapsular antibody response of Chilean infants to a single dose of Haemophilus influenzae type b capsular polysaccharide-tetanus toxoid conjugate, vaccine is substantially higher than that observed among infants of similar age from the USA. Comparison of selected demographic and environmental factors indicates that low maternal education and a greater number of persons in the home are significantly associated with the superior responder phenotype. High anticapsular antibody responses were associated with high antibody responses to tetanus toxoid, the carrier protein in this conjugate, but not to diphtheria toxoid. These data suggest that environmental factors may enhance the magnitude of the primary antibody response to PRP-T vaccine.

[Trial of prevention of severe Haemophilus influenzae type b infections and trial of tolerance, after PRP-T vaccination, in the Val-de-Marne region]. / Essai de prévention des infections graves à Haemophilus Influenzae type b et essai de tolérance, après vaccination PRP-T, dans le département du Val-de-Marne.

BACKGROUND: Protein-polysaccharide conjugate H influenzae vaccine is now routinely recommended for infants. To assess the vaccine's protective efficacy against invasive H influenzae infections and its safety, we conducted a study in the Val-de-Marne area of France. METHODS: From April 1991 to April 1993, 22,443 children less than 5 years of age were given PRP-T vaccine. Infants less than 6 months were given three doses whereas those between 6 and 12 months received only two doses, and children over 1 year of age received one dose. According to the infant's DTP-IPV vaccination status, PRP-T was administered alone or reconstituted extemporaneously with DTP-IPV. The immunogenicity of the conjugate vaccine was assessed after three doses in 100 infants under the age of 6 months. RESULTS: The PRP-T vaccine administered alone was safe. The reactions were more frequent when PRP-T vaccine was combined with DTP-IPV vaccine but they were comparable in frequency and severity to those observed after DTP-IPV vaccination. Before 1992, 18 Hib infections were reported each year in the Val-de-Marne region. During the study, only three Hib infections were reported each year. CONCLUSIONS: The fall in incidence of Hib infections, greater than expected, suggests a widespread immune effect of the vaccine, possibly due to a decrease in Hib nasopharyngeal carriage. The antibody titres to each component of vaccine were comparable to those observed in previous clinical infant studies.

Maternal immunization with Haemophilus influenzae type b polysaccharide-tetanus protein conjugate vaccine in The Gambia.

OBJECTIVE: To evaluate maternal responses to Haemophilus influenzae type b (Hib) polysaccharide-tetanus protein conjugate (polyribosylribitol phosphate-tetanus or PRP-T) given to pregnant Gambian women, the transplacental transfer of antibody, and the effect of maternal immunization on infant responses to the vaccine. DESIGN: An open, randomized immunogenicity study. SETTING: A busy urban health center in The Gambia. STUDY PARTICIPANTS: A total of 451 pregnant women enrolled during the third trimester of pregnancy. INTERVENTION: Study participants were randomized to three groups. In one group, mothers were given PRP-T during the third trimester and their infants were given PRP-T at 2, 3, and 4 months of age. In the second group, mothers received PRP-T and infants were given inactivated poliovirus vaccine. In the third group, mothers received meningococcal A and C vaccine, and their infants received PRP-T. MAIN OUTCOME MEASURES: Anti-PRP antibody measurements of maternal cord, and infant blood. RESULTS: Vaccinated women had a marked increase in total anti-PRP antibody (geometric mean titer 9.0 micrograms/mL), which was greatest in women in their first or second pregnancy. Previous tetanus vaccination during the same pregnancy and high concentrations of antitetanus antibody were associated with lower anti-PRP responses. In infants of PRP-T recipients, cord blood anti-PRP IgG concentrations were 61% of simultaneous maternal concentrations. In vaccinated infants of vaccinated mothers, geometric mean anti-PRP antibody concentrations at birth, 2 months of age, and 5 months of age were 1.92, 0.35 and 2.84 micrograms/mL, respectively, while in vaccinated infants of unvaccinated mothers, the corresponding concentrations were 0.29, 0.12, and 3.91 micrograms/mL. At 2 months of age, 60% of infants of vaccinated mothers and 26% of infants of unvaccinated mothers had anti-PRP antibody concentrations considered to be protective (>0.15 micrograms/mL). CONCLUSIONS: In areas where much invasive Hib disease occurs in infants younger than 6 months, maternal immunization may help to reduce the risk of Hib disease in infants too young for immunization.

Simultaneous injection of plasma-derived or recombinant hepatitis B vaccines with yellow fever and killed polio vaccines.

Previous studies have shown an absence of interaction between hepatitis B (HB) vaccine and other vaccines used in EPI programmes except for an apparent decrease of yellow fever antibody levels when hepatitis B and yellow fever vaccines are given simultaneously. We have therefore reinvestigated the interaction of these two vaccines and assessed the absence of interaction between inactivated polio vaccine and recombinant or plasma-derived HB vaccine. The immune responses to polio vaccine injected simultaneously with plasma-derived or recombinant HB vaccine were observed to be equivalent and similar to those observed in the literature. In this randomized study, the immune responses to yellow fever injected simultaneously with plasma-derived or recombinant HB vaccine were comparable to those observed after separate administration of each vaccine. Moreover, no increase in adverse reactions was noted.

Combined vaccination against yellow fever and typhoid fever: a comparative trial.

In order to evaluate a combination of yellow fever and typhoid fever vaccine, we conducted a controlled trial comparing reactogenicity and immunogenicity of Vi polysaccharide (ViPS) vaccine and yellow fever 17D (YF) vaccine after single, simultaneous and combined administration. The combined YF/ViPS vaccine was prepared by using the liquid ViPS vaccine as a diluent for the YF vaccine. The stability of such a reconstitution had been assessed in vitro. Safety was evaluated using a self-surveillance form and by repeated clinical visits. Immunogenicity was evaluated by a plaque reduction test for YF and by radioimmunoassay for ViPS. Tolerability was satisfactory in all groups. There was no increase in local or general reactions in groups receiving both vaccines, whether given simultaneously or combined. The serological response to ViPS was similar after single and simultaneous or combined administration. Interestingly, the immune response to YF was significantly enhanced in groups receiving the vaccines simultaneously or combined, suggesting a potential adjuvant effect of ViPS.

Safety and immunogenicity in young infants of Haemophilus b-tetanus protein conjugate vaccine, mixed in the same syringe with diphtheria-tetanus-pertussis-enhanced inactivated poliovirus vaccine.

Because inactivated poliovirus vaccine (IPV) and Haemophilus influenzae b vaccine are advised in many programs and may be incorporated further in other programs, we undertook a study to determine whether the administration of a tetravalent preparation of diphtheria-tetanus-pertussis-IPV mixed in one syringe with tetanus-conjugate H. influenzae b vaccine (DTP-IPV-PRPT) is associated with increased reactogenicity or interference with immunogenicity of individual vaccine components. In a placebo-controlled, double blind study, a total of 161 infants were enrolled (80 DTP-IPV-PRPT and 81 DTP-IPV-placebo). Vaccine was administered at 2, 4 and 6 months of age. Oral poliovirus vaccine was added at 7 months of age and a booster of oral poliovirus vaccine and DTP-IPV was also administered at 12 months of age, according to the policy in Israel. Local and systemic side effects were similar in both groups except for irritability after the second dose and use of acetaminophen which we observed slightly but significantly more often in the DTP-IPV-PRPT recipients. After the third dose the geometric mean titers of anti-polyribosyl-ribitol phosphate antibodies were 3.7 and 0.05 micrograms/ml in the PRPT and placebo groups, respectively (P < 0.001). Higher tetanus antitoxin titers were observed among recipients of DPT-IPV-placebo (1.1 IU/ml vs. 0.7 IU/ml, P = 0.003). A similar trend was found for pertussis agglutinin titers (93.4 vs. 65.4, P = 0.054). No difference was observed for anti-diphtheria toxoid and poliovirus 1, 2, and 3.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunogenicity of a recombinant Pre-S2-containing hepatitis B vaccine versus plasma-derived vaccine administered as a booster.

GenHevac B Pasteur is a recombinant hepatitis B vaccine derived from a mammalian cell line and containing HBs as well as pre-S2 antigens. Its immunogenicity was compared to that of the plasma-derived vaccine Hevac B Pasteur in a population primovaccinated 5.5 years earlier with four injections of the same plasma vaccine. The booster injection with either GenHevac or Hevac was administered to 295 subjects with residual anti-HBs titres below 500 IU/l (group 1: 0-9; group 2: 10-99; group 3: 100-499 IU/l). After four weeks, GenHevac had induced higher anti-HBs responses than Hevac in all groups, particularly among the low responders of group 1. Response to the vaccine occurred earlier with GenHevac. Mean anti-pre-S2 production was moderate in all groups for both vaccines (GenHevac: 60 IU/l; Hevac: 31 IU/l) and was not found in the 32 subjects who produced less than 100 IU/l anti-HBs. The results of the present study indicate that GenHevac is at least as immunogenic as Hevac.

The immunogenicity and safety of Haemophilus influenzae type b-tetanus toxoid conjugate vaccine in Gambian infants.

In developing countries, Haemophilus influenzae type b is a major cause of meningitis and pneumonia in the 1st year of life. The safety and immunogenicity of a Haemophilus influenzae type b polysaccharide-tetanus toxoid conjugate vaccine (PRP-T) were evaluated in two studies of Gambian infants. In the first study, 131 infants were recruited and randomized into three groups to receive PRP-T at 1 and 3 months (group A), PRP-T at 2 and 4 months (group B) or no PRP-T (group C). The liquid form of PRP-T was used. The geometric mean titre (GMT) of anti-PRP antibody 1 month after the second dose was 0.26 microgram/ml in group A and 0.41 microgram/ml in group B. In the second study, 66 infants were given PRP-T in the lyophilized form at 2, 3 and 4 months of age. The GMT 1 month after the first dose was 0.09 microgram/ml, after the second 0.74 microgram/ml and after the third 2.32 micrograms/ml. After the third dose, 72% of children had antibody levels greater than 1.0 microgram/ml and 93% greater than 0.15 microgram/ml. No serious side-effects were observed and the rate of adverse reactions was consistent with the concurrent administration of diphtheria-tetanus-pertussis (DPT) vaccine.

PIP: In Sukuta, Gambia, in 1989, 128 newborns were randomly allocated to receive the liquid form of the Haemophilus influenzae type b (Hib) polysaccharide-tetanus toxoid (PRP-T) vaccine at 1 and 3 months (group A), 2 and 4 months (group B), or not to receive the vaccine (group C). All these children also received the oral polio vaccine and the diphtheria-pertussis-tetanus (DPT) vaccine. In 1990, in Bakau, Gambia, 66 infants received the lyophilized form of the PRP-T vaccine at the same time as they received DPT vaccine: 2, 3, and 4 months. The investigators aimed to determine the safety and immunogenicity of PRP-T as a forerunner to the upcoming PRP-T efficacy trial in Gambia. In the 1989 study, the geometric mean titer (GMT) of anti-PRP antibody 1 month after the second dose was higher in group B than in group A (0.41 vs. 0.26 mcg/ml). In the 1990 study, the GMT of anti-PRP antibody was 0.09 mcg/ml after the first dose, 0.74 mcg/ml after the second dose, and 2.32 mcg/ml after the third dose. One month after the final dose, the lyophilized PRP-T vaccine yielded higher antibody levels than the liquid form. For example, 72% of infants in the lyophilized group had an antibody level greater than 1 mcg/ml compared with 18% for the liquid group. 93% of all infants in groups A and B had antibody levels above 0.15 mcg/ml, the level considered to provide immediate protection, compared with 53% for the liquid group. Serious side effects were not observed. The rate of adverse reactions correlated with the concurrent delivery of DPT vaccine. Advantages of the PRP-T vaccine include: it mixes well with DPT; if administered in a three-dose schedule to Gambian infants, it is safe and elicits a protective antibody response in most infants; and it also protects against Hib infection, a major cause of meningitis and pneumonia in infants and an important cause of major childhood-acquired disability in developing countries.