[Introduction of vaccination against human papillomavirus in developing countries: update and perspectives]

Cervical cancer and other diseases related to human papillomavirus (HPV) represent a global public health problem. Safe and effective vaccines are now available and already used in many industrialized countries. Immunization offers the best hope for protecting the population against a disease that is the second most deadly cancer in the developing world and the first most deadly in Africa. The World Health Organization currently recommends introduction of HVP vaccination in developing countries. Widespread vaccination could be beneficial in numerous domains other than primary prevention of cervical cancer. Efforts to overcome the numerous obstacles and speed up implementation of HVP vaccination programs are now underway in many areas ranging from related scientific issues such as epidemiology and clinical research to administrative concerns such as healthcare economics, vaccination guidelines, public acceptation, program funding, and universal access. Vaccine manufacturers have committed themselves to working in partnership with national and international organizations to ensure access to HPV vaccine for all countries regardless of economic level, Although numerous issues must be resolved to optimize the use of HPV vaccines and ensure synergistic integration of vaccination, screening and treatment, current initiatives and efforts should allow introduction of HPV vaccination in developing countries in a not too distant future.

Impact of osmolality on burning sensations during and immediately after intramuscular injection of 0.5 ml of vaccine suspensions in healthy adults

A randomised placebo controlled double-blind cross-over trial was performed on twenty healthy adults to assess the effect of osmolality (300,600,850 and 1100 mOsm) on local tolerance of an intramuscular injection (0.5 ml) of five suspensions containing the same components as the excipients of a combined Diphtheria-Tetanus-acellular Pertussis-inactivated Poliomyelitis-Haemophilus influenzae type b paediatric vaccine (DtacP-IPV-Hib, PENTAVAC). The results did not show any dose-effect relationship between burning or pain sensations and the different osmolalities tested. Although mild and not clinically relevant, these sensations seemed to occur more frequently following injection of an isotonic saline solution (P<0.05). Thus, the osmolality of vaccine like suspensions does not appear to be a potential cause of local pain or burning sensation after their administration.

Immunogenicity and safety of a new liquid hexavalent combined vaccine compared with separate administration of reference licensed vaccines in infants

OBJECTIVE

The immunogenicity and safety of a new liquid hexavalent vaccine (diphtheria-tetanus-acellular pertussis-inactivated polio vaccine-hepatitis B-polyribosyl ribitol phosphate conjugated to tetanus protein; Hexavac; Aventis Pasteur MSD, Lyon, France) are compared with those of reference vaccines [diphtheria-tetanus-acellular pertussis-inactivated polio vaccine reconstituting lyophilized purified Haemophilus influenzae polysaccharide conjugated to tetanus protein vaccine (Pentavac; Aventis Pasteur MSD) and hepatitis B vaccine (H-B-Vax II; Aventis Pasteur MSD)] injected separately at the same visit in a prospective multicenter, comparative, open label trial.

METHODS

Infants were randomized to receive Hexavac (n = 423) or Pentavac and H-B-Vax II (n = 425) as a primary immunization series at 2, 4 and 6 months of age. Seroprotection and seroconversion rates against all antigens at 1 month after the primary series were compared between the two vaccine groups with 95% confidence intervals (CI0.95) and were considered clinically equivalent (not inferior) when the upper limit of the 95% confidence interval on the difference (reference, hexavalent) was below predefined differences.

RESULTS

Hexavac met and surpassed the pre-defined criteria for clinical equivalence to Pentavac and H-B-Vax II given concomitantly. It elicited similar seroprotection and seroconversion rates against all antigens. Seroprotection and seroconversion rates obtained 1 month after the third dose of Hexavac were >90% for all antigens. The postimmunization antibody geometric mean titers (GMT) for hepatitis B and purified Haemophilus influenzae polysaccharide were about 2-fold higher in infants who received the reference vaccines than in infants who had received Hexavac. GMTs for poliovirus antibodies tended to be enhanced in infants vaccinated with Hexavac. GMTs for all other antigens were very similar among both groups. Hexavac was generally well-tolerated. At least one local reaction was reported in 20.3% of Hexavac injections compared with 15.8% at the Pentavac injections site and 3.8% at the H-B-Vax II injections site. These reactions were generally mild and transient. At least one systemic adverse event was reported in 45.7% of Hexavac injections compared with 42.2% of Pentavac and H-B-Vax II injections (mild fever, irritability and drowsiness were most frequently reported). The frequency of adverse events was not significantly different between groups. No vaccine-related serious adverse event occurred during the study.

CONCLUSION

This liquid hexavalent vaccine was generally well-tolerated and provided immune responses adequate to be protective against six infectious diseases with a single injection, given at 2, 4 and 6 months of age.

Experience with Salmonella typhi Vi capsular polysaccharide vaccine

Typhoid fever remains an important health threat in many parts of the world, with an estimated 16 million cases and 600,000 deaths occurring each year. The emergence of Salmonella typhi strains multiply resistant to antibiotics has complicated the treatment of this disease. Field experience of 8 years shows that a vaccine composed of purified Vi capsular polysaccharide of Salmonella typhi, given as a single intramuscular or deep subcutaneous injection, has consistent immunogenicity and efficacy. Side effects, based on reports since 1989, are infrequent and mild. Furthermore, the Vi vaccine may be administered simultaneously with other common "travel" vaccines, at two different sites of injection, without affecting immunogenicity and tolerability. This review presents an update of the development and clinical experience with the Salmonella typhi Vi polysaccharide vaccine (Typhim Vi; Pasteur Mérieux Connaught, France).

The immunogenicity and safety of a new combined diphtheria, tetanus and poliomyelitis booster vaccine (Td-eIPV)

In view of the continuing risk of contracting tetanus, diphtheria and poliomyelitis, and the well-documented decline in immunity with time, the need for booster vaccinations is substantial. The immunogenicity and safety of a new combined booster vaccine against tetanus, diphtheria and poliomyelitis (REVAXIS) developed by Pasteur Mérieux Connaught (Lyon, France) were evaluated in four clinical studies. This vaccine (Td-eIPV) combines an adsorbed tetanus toxoid and low-dose diphtheria toxoid vaccine (Td) with an enhanced, inactivated polio vaccine against poliovirus types 1, 2 and 3 (eIPV). In 256 healthy young adults, a single dose of Td-eIPV was shown to be immunogenic, eliciting antibody levels considered protective against disease for each vaccine component in > or = 99.6% of the subjects. In 112 healthy older subjects (> 40 years of age), two doses of Td-eIPV elicited seroprotective levels of antibodies in 94% of the subjects for diphtheria, and in all subjects for tetanus and poliovirus types 1, 2 and 3. Safety data from all 368 subjects, as well as 31 phase I volunteers and 1,742 subjects included in a safety study, reveal that the vaccine is safe. Most reactions were predictable, temporary and mild. There was no evidence that the vaccine was associated with any clinically serious event or modification of clinical laboratory parameters. The data reviewed here show that Td-eIPV is immunogenic and safe when administered as a booster vaccination in healthy adults of all ages.

Human diploid cell strains (HDCS) viral vaccines

Since the development in 1961 by Hayflick and Moorhead of a human diploid cell strain (HDCS) culture system for isolating viruses, HDCS-derived human vaccines have been licensed worldwide for polio IPV and OPV (multiple strains), rabies (Pitman-Moore L503 3M strain); rubella (RA27/3 strain); measles (Edmonston-Zagreb strain); varicella-zoster (Oka strain); mumps (Rubini strain) and hepatitis A (HM-175, CR-326-F', and GBM strains). Many of these widely-used vaccines now have at least a 20-year record of safety after extensive, ongoing pharmacovigilance. Serious vaccine-associated events are rare, and appear to reflect the activity of the live viruses replicated in the HDCS or of the inactivated viruses or other proteins added during manufacture. There is no credible association of reactions to the HDCS substrate or a hypothetical contaminant derived from it.

[Efficacy of pneumococcal vaccination]

POLYVALENT VACCINE: Pneumococcal vaccination is based on the antigenic properties of polysides carried on the bacterial capsule which induce production of bactericidal serotype-specific antibodies. The 23 serotypes contained in the current vaccine cover 85 to 90% of all strains observed in pneumococcal infections in Europe.

PROVEN EFFICACY

Prospective and retrospective studies have demonstrated that pneumococcal vaccination can prevent 60 to 80% of invasive pneumococcal infections in immunocompetent elderly subjects and/or persons in high-risk groups with underlying disorders.

TARGET POPULATION

Immunocompetent persons in the 60-65 year and older age group comprise the target population for pneumococcal vaccination. Incidence and mortality of pneumococcal infections is high in this group. Simple vaccination strategies should be implemented.

[Aseptic meningitis after mumps vaccination]

The aim of this retrospective study was to evaluate the incidence and the characteristics of spontaneously reported aseptic meningitis (AM) in France following mumps vaccination with monovalent or multivalent vaccines containing the Urabe strain. Fifty-four cases of AM were reported to the regional drug surveillance centres or to the manufacturer from the time each vaccine was launched up until June 1992. Twenty cases were associated with the time off administration of a monovalent mumps vaccine and 34 with a trivalent measles, mumps and rubella vaccine (MMR). A mumps virus was isolated in four cases in the cerebrospinal fluid and an Urabe-like strain was characterised twice by polymerase chain reaction (PCR). A probable mumps origin was assumed in 17 other cases where the patients presented with other clinical or biological signs of mumps infection. The clinical outcome of AM was always favourable. The global incidence of mumps vaccine-associated AM was 0.82/100,000 doses, which is significantly lower than the incidence in the unvaccinated population. Even considering that the actual incidence of AM is much higher when assessed by active surveillance studies, the risk/benefit ratio of mumps vaccine remains in favour of vaccination. The incidence of mumps vaccines containing Jeryl Lynn (ROR Vax et Imu ORR) associated with AM needs to be evaluated.

[Thrombocytopenic purpura after isolated or combined vaccination against measles, mumps and rubella]

A retrospective epidemiological survey was conducted to evaluate the incidence and characteristics of thrombocytopenic purpura (TP) reported in France following measles, mumps or rubella vaccination with monovalent or multivalent vaccines. Sixty cases of TP were reported i.e an incidence/100,000 doses of 0.23 and 0.17 for measles or rubella vaccines respectively given alone, to 0.87 for combined measles-rubella vaccine and 0.95 for MMR vaccine. The mean age was 21 +/- 12 months and the delay of diagnosis was 16 +/- 6 days after vaccination. Thrombopenia was severe (mean platelet count: 8000 +/- 6000/mm3) and always associated with purpura. The immediate outcome was favourable in 89.5 per cent of cases. Vaccine-associated TP appears to be similar to acute childhood idiopathic thrombocytopenic purpura but the clear temporal relationship between MMR vaccination and the occurrence of TP make a causal relationship highly plausible. Acute TP seems a rare complication of measles-rubella and MMR vaccination but clinicians had to be informed of the possibility of their occurrence. Acute TP following vaccination should be reported by physicians to their Regional Drug Surveillance Centre.

Aseptic meningitis following mumps vaccine: a retrospective survey by the French Regional Pharmacovigilance centres and by Pasteur-Mérieux Sérums & vaccins

Since 1989 many case series and observational studies of aseptic meningitis (AM) associated with the use of live attenuated mumps vaccines containing the Urabe AM9 strain have been reported worldwide. The aim of this retrospective reported AM in France following mumps vaccination with monovalent or multivalent vaccines containing the Urabe strain. Fifty-four cases of AM were reported to the Regional Pharmacovigilance centres or to the manufacturer from the time each vaccine was launched up until June 1992. Twenty cases were temporally associated with the administration of a monovalent mumps vaccine and 34 with a trivalent measles, mumps and rubella vaccine (MMR). A mumps virus was isolated in four cases in the cerebrospinal fluid and an Urabe-like strain was characterized twice by polymerase chain reaction (PCR). A probable mumps origin was assumed in 17 other cases where the patients presented with other clinical or biological signs of mumps infection. The clinical outcome of AM, known in 87% of the population, was always favourable. The global incidence of mumps vaccine-associated AM was 0.82/100,000 doses, which is significantly lower than the incidence in the unvaccinated population. Even considering that the actual incidence of AM is much higher when assessed by active surveillance studies, the risk/benefit ratio of mumps vaccine remains in favour of vaccination.

Thrombocytopenic purpura after measles, mumps and rubella vaccination: a retrospective survey by the French regional pharmacovigilance centres and pasteur-mérieux sérums et vaccins

BACKGROUND

Thrombocytopenic purpura (TP) after vaccination with measles, mumps and rubella has occasionally been reported.

OBJECTIVES

To evaluate the incidence and characteristics of thrombocytopenic purpura reported in France after measles, mumps or rubella vaccination with monovalent or multivalent vaccines.

METHODS

A retrospective epidemiologic survey was conducted. All confirmed cases of TP reported spontaneously either to the French Regional Pharmacovigilance Centres or to the manufacturer (Pasteur-Mérieux Sérums et Vaccins) between 1984 and June 30, 1992, were reviewed.

RESULTS

Sixty cases of TP in children between 1 and 11 years of age occurred 2 to 45 days after administration of 1 of 7 vaccines. The reported incidence of TP varied from 0.17 and 0.23/100,000 doses of measles or rubella vaccines, respectively, given alone to 0.87/100,000 doses of combined measles-rubella vaccines and 0.95/100,000 doses of the measles-mumps-rubella vaccine. The mean platelet count was 8000 +/- 6000/mm3 and was lower than 10,000/mm3 in 58% of cases. The immediate outcome was favorable in 89.5% of cases.

CONCLUSIONS

According to the clinical course and biologic findings, vaccine-associated TP appears to be similar to that occurring after natural measles or rubella infections and is not distinguishable from acute childhood idiopathic thrombocytopenic purpura not associated with vaccination. Such observations, combined with a clear temporal relationship between measles-mumps-rubella vaccination and the occurrence of TP, make a causal relationship highly plausible. Nevertheless the incidence of these events remains relatively low with a favorable immediate outcome.

Immunogenicity and safety of a 23-valent pneumococcal polysaccharide vaccine in healthy children and in children at increased risk of pneumococcal infection

Splenectomized children as well as those suffering from nephrotic syndrome or recurrent asthmatic bronchitis have an increased susceptibility to systemic pneumococcal infections compared to healthy children. To determine the immunogenicity and safety of a 23-valent pneumococcal polysaccharide vaccine (PPV), 119 children (21 healthy, 26 splenectomized children, 48 with nephrotic syndrome and 24 with recurrent asthmatic bronchitis), aged 2-18 years, received one subcutaneous injection of a 23-valent PPV. Anti-capsular antibodies (Ab) to types 6B, 9V, 14, 18C, 19F and 23F were measured by ELISA before and 4 weeks after immunization. In all cases the adverse reactions were mild and transient, consisting of local pain and/or erythema or swelling in 41% and fever above 38.5 degrees C in 2% of the children. The healthy children responded well to vaccination with a mean fold increase (FI) of 2.6 in postvaccination Ab titers compared to prevaccination titers. The combined geometric mean Ab concentrations in the high-risk children were significantly lower than those of healthy children both before and after vaccination. However, the combined geometric mean FI were not significantly different between high-risk and healthy children. These results indicate that PPV is immunogenic and safe in high-risk as well as in healthy Korean children.

Haemophilus type B conjugate vaccine: postimmunization kinetics of IgM and IgG antibody responses in ten vaccinated children

A new Haemophilus type b conjugate vaccine coupling capsular polysaccharide of Haemophilus influenzae b to tetanus toxoid is available in France and other countries. We have studied the kinetics of the immune response in ten children aged 17 to 50 months during the 4 weeks after immunization with one dose of Haemophilus type b conjugate vaccine. Eight serum samples were collected from each child at day 0 (D0), D2, D4, D7, D10, D14, D21 and D28. An ELISA method has been used to discriminate between IgM and IgG classes of anti-polyribosylribitol phosphate antibodies. A high level of IgM appeared at D7 and persisted until D28. The increase in IgG was regular and progressive from D7.

Immunogenicity of Haemophilus influenzae type b conjugate vaccine in allogeneic bone marrow recipients

A randomized study was conducted in 40 allogeneic marrow recipients to compare the immunogenicity of two Haemophilus influenzae type b (Hib) vaccines (either the Hib capsular polysaccharide [Hib-CPS] or tetanus toxoid-conjugated Hib-CPS [Hib-CPS-T]). A second injection consisted of Hib-CPS-T. Before immunization, 3 patients had serum antibody levels > 1 microgram/mL. After the first injection, the response was better after Hib-CPS-T than after Hib-CPS but lower than in normal subjects; a number of patients lacked any IgG antibody response, especially after Hib-CPS. Of patients who received two injections of Hib-CPS-T, 85% achieved an antibody concentration > or = 1 microgram/mL. Hib-CPS-T induced a response in IgG2-deficient patients whereas Hib-CPS alone did not. IgG antibodies predominantly belonged to the IgG1 subclass. The antibody response was better in patients immunized late after graft. This study shows that Hib-CPS-T is more immunogenic than Hib-CPS in marrow recipients.

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

As new vaccines are developed there is increasing interest in reducing the number of injections given to children by combining vaccines in one syringe. We studied the safety and immunogenicity of Haemophilus influenzae type b-tetanus protein conjugate vaccine (PRP-T) administered at ages 2, 4 and 6 months mixed in the same syringe with DTP vaccine and its effects on the seroresponse to DTP vaccine. A group of 112 healthy 2-month-old infants received DTP-PRP-T or DTP-placebo mixed immediately before immunization in the same syringe. The addition of PRP-T to DTP did not increase the rate of local or systemic reactions. After the first, second and third dose, the PRP-T recipients showed a geometric anti-PRP antibody mean of 0.13, 2.31 and 6.40 micrograms/ml vs. 0.07, 0.05 and 0.05 micrograms/ml among the DTP-placebo recipients, respectively. Of the PRP-T recipients, 94 and 98% attained antibody concentration of greater than or equal to 0.15 micrograms/ml protein after the second and third dose, respectively, and 65 and 94% attained a concentration of greater than or equal to 1.0 micrograms/ml after the second and third dose, respectively. At the age of 1 year 94 and 52% of the DTP-PRP-T recipients vs. 12% and 0% of the placebo recipients still maintained titers of greater than or equal to 0.15 and greater than or equal to 1.0 micrograms/ml, respectively. The administration of DTP in the same syringe with PRP-T did not affect significantly the antibody response to diphtheria and tetanus toxoid and to pertussis agglutinins. It is concluded that PRP-T vaccine could be administered in the same syringe as DTP.

Evaluation of the efficacy of a low-passage bovine rotavirus (strain WC3) vaccine in children in Central Africa

The safety and efficacy of a WC3 rotavirus vaccine was evaluated in a double-blind placebo-controlled trial involving 472 children in Bangui (Central African Republic). Each child received two doses of either placebo (235 children) or vaccine (237 children) at a 1-month interval, the first dose being given at 3 months of age. During the follow-up survey 9 months after the first dose, 117 rotavirus diarrhoeas were observed, 59 in the placebo group, 58 in the vaccinated group. The only positive effect of the vaccine was a significantly higher proportion of mild rotavirus diarrhoeal episodes in the vaccinated group than in the placebo group. Of the children in the vaccinated group, 60% had a positive immune response to WC3 rotavirus when tested by plaque reduction seroneutralization.

Reactogenicity and immunogenicity of rotavirus WC3 vaccine in 5-12 month old infants

Rotavirus is a major cause of acute gastroenteritis in infants worldwide and there is need for an effective vaccine. Rotavirus Wistar calf 3 (WC3) is a strain of bovine origin attenuated by 12 passages in cell culture. A lyophilized candidate vaccine containing 1 x 10(7) PFU of WC3 has been developed. An oral dose was given to 25 French infants 5-12-months old (mean age 8.6 months). No diarrhoea was observed within 2 weeks after vaccination. Unexplained vomiting was reported once and isolated fever greater than 37.8 degrees C was reported 3 times during the first week. One month later, a neutralizing antibody response to serotypes tested was shown in 88% of cases, with heterotypic responses to human serotype 3 (SA11 strain) in 72% and to type 1 (WA strain) in 48%. The percentage of immune response was similar whether the infant had antibody prior to immunization or not, but a booster effect was observed in children who had pre-immunization rotavirus antibodies. Considering these promising results, efficacy trials are in the planning in different parts of the world.

[Tolerance and immunogenicity of the capsular polyoside vaccine against Haemophilus influenzae type b. A study of 325 children 15 to 71 months of age]

The antigenic properties of the capsule polyoside (PRP) from Haemophilus influenzae type b (Hib) are adequate to form the basis for immunization designed to prevent the severe infections caused by this organism. The tolerance and immunogenicity of a vaccine containing either 12.5 or 25 micrograms PRP were studied in 325 healthy children aged 15 to 71 months after informed consent had been obtained from the parents. Each child was given one subcutaneous injection of 0.5 ml vaccine. Antibodies against Hib were assayed before and one month after the injection. Clinical tolerance was outstanding both locally (moderate and transient pain in 13% of cases) and systematically, with only eight (2.6%) febrile reactions in excess of 38.5 degrees C within 24 hours after the injection. A very significant rise in antibody titers was seen in all age groups, but a mean titer of 1 microgram/ml was achieved only in children aged 24 months or more. No significant difference was found between the two dosages. Individual analysis showed that following immunization antibody titers reached 0.15 micrograms/ml or more in 65% of infants aged 15 to 17 months, 71% of infants aged 18 to 23 months, 80% of infants aged 24 to 30 months and 95% of children older than 30 months. Despite the inadequate immune response evidenced in the younger age groups, our results confirm that Hib infections are preventable from the age of 2 years. Our results are consistent with those recorded with a similar vaccine in Finland.

Alterations in the human immune response to the hepatitis B vaccine among the elderly

The specific binding of hepatitis B (HBs) antigen by lymphocytes from old people immunized with hepatitis B vaccine was explored. For that purpose HBs antigen was combined with fluorescent microspheres, and labeled antigen was allowed to react with lymphocytes from HBs vaccine-responsive or unresponsive people. Lymphocytes from 10 responders and 14 nonresponders were tested for their antigen-binding ability. For controls, lymphocytes were incubated with microspheres bearing human albumin. Lymphocytes from 8 out of 10 responders were able to recognize HBs antigen; for the nonresponders the ratio was 9 out of 14. HBs-binding lymphocytes were B cells but not T lymphocytes. B and T cells from responders and nonresponders were combined and cultivated for 8 days in the presence of HBs antigen, and antibody-producing cells were counted. Neither B cells alone nor B cells plus T cells from nonresponders were able to produce antibody. On the other hand B cells from unresponsive old people produced antibodies when they were cultivated in the presence of HBs antigen and T cells from responsive old people. These data suggest that some elderly individuals who do not produce antibody after in vivo immunization by HBs vaccine do have antibody-producing cells. Instead of a gap in their immune repertoire, these people are suffering from immune dysfunction.

[Study of insulin secretion in chronic pancreatitis]

17 oral glucose tolerance tests with simultaneous estimation of plasma insulin, were carried out in 15 patients with chronic pancreatitis of which 7 were of calcific type. Among these patients, 10 had obvious diabetes and 3 chemical diabetes. The disorders of glucose regulation were more common in the calcific form of the disease. Serum insulin was then lower and not stimulant. The curves of plasma insulin obtained in non-calcific pancreatitis were variable. In hyperinsulinism, the oral glucose tolerance test showed flat or normal curves. In hypoinsulinism, the glucose tolerance tests were either normal or strongly pathological. This insulinism, as shown by this study of chronic pancreatitis, seems to be linked to an imbalance in the cell distribution of the islets of Langerhans. The role of glucagon appears preponderant.