Immunogenicity and reactogenicity of a novel hexavalent DTPa-HBV-IPV/Hib vaccine compared to separate concomitant injections of DTPa-IPV/Hib and HBV vaccines, when administered according to a 3, 5 and 11 month vaccination schedule

In an open randomised trial, 312 eligible infants were enrolled to receive either a single injection of the hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B virus-inactivated polio/ Haemophilus influenzae b (DTPa-HBV-IPV/Hib) vaccine, or concomitant injections of commercial DTPa-IPV/Hib and HBV vaccines (comparator). Vaccines were administered at 3, 5 and 11 months of age. The statistical approach for non-inferiority showed that the DTPa-HBV-IPV/Hib vaccine was at least as immunogenic as the comparator vaccines in terms of immunogenicity of all antigens 1 month after the 2nd dose. Non-inferiority criteria were also met immediately before and 1 month after the 3rd dose for all antigens except poliovirus type 3 prior to the 3rd dose. The majority of subjects were seroprotected against diphtheria, tetanus, polyribosyl-ribitol-phosphate, hepatitis B and poliovirus after the 2nd dose and maintained seroprotective antibody levels until the 3rd dose. A marked difference was observed in anti-HBs antibody geometric mean antibody concentrations (GMCs) at 1 month after the 2nd dose (higher GMCs in DTPa-HBV-IPV/Hib group). Reactogenicity (incidence of solicited local and general symptoms) was similar between the two study groups and no vaccine-related serious adverse events occurred.

CONCLUSION

the new diphtheria-tetanus-acellular pertussis-hepatitis B virus-inactivated polio/ Haemophilus influenzae b vaccine administered at 3, 5 and 11 months of age was safe and at least as immunogenic as the comparator vaccines thus providing an effective and more comfortable option for this infant vaccination schedule.

Vaccination against Haemophilus influenzae type b and atopy in east German schoolchildren

INTRODUCTION

Although routine childhood immunisations are known to prevent severe diseases there is an ongoing discussion on possible side effects in later life. In this paper we investigated the association of Haemophilus influenzae type b (Hib)-vaccination and atopic diseases and allergic sensitisation in children in Eastern Germany.

METHODS

From 1998-1999 a cross-sectional survey of school children aged 5 to 14 years on long-term health effects of air pollution was conducted in three regions of Eastern Germany. Atopic outcome was defined by parental reporting of wheezing and doctor's diagnosed asthma (including asthma-like bronchitis), hay fever and eczema. Specific serum IgE against 5 aeroallergens were analysed by RAST-technique. Vaccination status was assessed by vaccination records from the respective local health authorities. Analysis is restricted to 1943 children with complete information on age, gender, place of residence, parental education and 1676 children with available blood data.

RESULTS

Lifetime prevalence were 4.9% for asthma, 21.1% for wheezing, 6.6% for hay fever, 11.4% for eczema. 32% of the children had at least one specific IgE RAST>0. Hib-vaccination coverage was 42 % overall, 93 % in 5-7 yr olds, 59 % in 8-10 yr olds and 11 % in 11-14 yr olds. Odds Ratios adjusted for age, gender, place of residence, and parental education were 1.86 (1.05-3.32) for asthma, 1.55 (0.95-2.54) for hay fever, 1.03 (0.70-1.50) for eczema and 1.25 (0.94-1.67) for at least 1 specific IgE RAST>0.

CONCLUSION

We found little evidence for an association between Hib-vaccination and some atopic outcomes and causality cannot be ascertained. Our findings do not give sufficient support to question the value of Hib vaccination given the substantial contribution of mass immunisations to public health. Specific research on possible long-term effects of vaccines is needed to enable final conclusions on this topic.

Impact of a birth dose of hepatitis B vaccine on the reactogenicity and immunogenicity of diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus-Haemophilus influenzae type b combination vaccination

OBJECTIVES

To assess the impact of a birth dose of hepatitis B vaccine (HepB) on the reactogenicity and immunogenicity of a novel diphtheria-tetanus-acellular pertussis (DTaP)- HepB-inactivated poliovirus (IPV)/ type b (Hib) combination vaccine administered subsequently at 2, 4 and 6 months of age.

METHODS

Neonates ( = 550) were randomized into two groups with regard to receipt of HepB at birth. All subjects in both groups received DTaP-HepB-IPV/Hib at 2, 4 and 6 months of age. Solicited local and general adverse events were recorded for 8 days after each dose. Antibodies to hepatitis B surface antigen were measured 1 month after the third dose of DTaP-HepB-IPV/Hib in a subset of 170 infants; titers of at least 10 mIU/ml were considered protective.

RESULTS

The DTaP-HepB-IPV/Hib combination vaccine was well-tolerated in both groups. Of the infants who received a birth dose of HepB, 22.6% had severe (Grade 3) reactions after any of the three doses of DTaP-HepB-IPV/Hib combination vaccine compared with 23.2% of subjects who did not receive a birth dose of HepB (difference, -0.5%; 90% confidence interval, -7.4 to 6.1). Antibody to hepatitis B surface antigen titers were > or =10 mIU/ml for all tested infants. Geometric mean titers were 2996.2 and 1240.1 mIU/ml with and without a birth dose of HepB, respectively.

CONCLUSIONS

A HepB birth dose does not increase the reactogenicity of a combination DTaP-HepB-IPV/Hib vaccine administered at 2, 4 and 6 months of age, and all tested subjects achieved protective anti-HBs titers (> or =10 mIU/ml), although geometric mean titers were higher when a birth dose of HepB was given.

Immunogenicity and reactogenicity of combined versus separately administered DTPw-HBV and Hib vaccines given to healthy infants at 2, 4 and 6 months of age, with a booster at 18 months

OBJECTIVES

To determine the immunogenicity and reactogenicity of a combined DTPw-HBV/Hib vaccine, in comparison with DTPw-HBV and Hib vaccines given as separate concomitant injections.

METHODS

In an open, randomized study, healthy infants were injected with either DTPw-HBV/Hib vaccine or separate DTPw-HBV and Hib vaccines at 2, 4 and 6 months of age, with a booster at 18 months.

RESULTS

Both vaccination regimens were immunogenic, with seropositivity rates of 100% after the booster vaccination for all vaccine components. Even as early as 2 months after the second dose of the primary vaccination, most patients had seroprotective antibody titers, the proportion of seropositive subjects approaching 100% for tetanus, hepatitis B, and Hib. Post-primary and post-booster geometric mean titers (GMTs) were well above seroprotective thresholds for each vaccine antigen in both groups, with no clinically relevant differences in the groups. The separate and combined administrations showed comparable reactogenicity profiles, and neither showed a significant increase in reactogenicity with successive doses.

CONCLUSIONS

The results of this study support the combination of Hib and DTPw-HBV vaccination in routine infant immunization at 2, 4 and 6 months of age with a booster at 18 months. Maximum benefit is obtained from compliance with the full course, but substantial benefit is likely to be achieved even in partially compliant patients, provided they receive at least two doses. Furthermore, these results demonstrate the tolerability of a fourth (booster) administration, where the addition of the Hib vaccine to DTPw-HBV did not lead to an increase in the overall reactogenicity.

Haemophilus influenzae type b vaccine formulation and risk of childhood leukaemia

Incidence of childhood leukaemia was studied among subjects of a vaccine trial in Finland comparing the polysaccharide-diptheria toxoid conjugate and oligosaccharide-CRM197 conjugate Haemophilus influenzae type b conjugate vaccine formulations. Eighty cases of childhood leukaemia were detected: 35 among children on the polysaccharide-diptheria toxoid conjugate arm, and 45 among children on the oligosaccharide-CRM197 conjugate arm, which was not statistically significant.

Lack of association between receipt of conjugate haemophilus influenzae type B vaccine (HbOC) in infancy and risk of type 1 (juvenile onset) diabetes: long term follow-up of the HbOC efficacy trial cohort

We evaluated the effect of infant vaccination with HbOC Haemophilus influenzae type b (Hib) conjugate vaccine on the risk of onset of type 1 juvenile diabetes later in life by examining data from a large controlled prospective Phase III clinical efficacy trial conducted within Northern California Kaiser Permanente between 1988 and 1990. The overall study population included children who were offered the Hib conjugate vaccine (acceptors and refusers) as well as a cohort of children who were systemically excluded from the trial on the basis of their birth date. These children are now 10 to 12 years of age. We found no evidence that vaccination with Hib conjugate vaccine in infancy is associated with risk of diabetes later in life.

Safety and immunogenicity of Haemophilus influenzae type B vaccine given in combination with DTwP at 6, 10 and 14 weeks of age

OBJECTIVE

To assess the immunogenicity and reactogenicity of a tetanus conjugate Haemophilus influenzae type b vaccine (Act-Hib) when extemporaneously mixed and administered as a DTwP-Hib combination using an Indian DTwP vaccine (BE DTwP) in comparison with a licensed DTwP-Hib combination vaccine.

METHODS

378 healthy infants were enrolled and randomly allocated to receive either three doses, at 6, 10 and 14 weeks of age, of Act-Hib in combination with BE DTwP (Group A, n = 160), TetrAct-Hib (Group B, n = 160), or BE DTwP and Act-Hib as separate injections (Group C, n = 58). Sera collected before the first dose and one month after the third dose were tested for antibodies to vaccine antigens. Safety was determined using parental diary cards.

RESULTS

Anti-Hib antibody concentrations indicative of short-term protection (> 0.15 g/ml) were elicited in all but one subject in Group A (99.3%), and all subjects in Groups B and C. The concentration of 1 g/ml, considered to provide long-term protection, was achieved in 96.7%, 100% and 98.2% of the infants in Groups A, B and C, respectively. All children displayed satisfactory responses to the three DTwP component antigens, TetrAct-Hib eliciting higher titers against diphtheria and tetanus than BE DTwP. No vaccine-associated serious adverse events occurred. The BE DTwP vaccine was associated with more reports of fever than TetrAct-Hib, but most symptoms were regarded as mild and all resolved without sequelae.

CONCLUSIONS

Combining Act-Hib and a local DTwP vaccine did not affect the anti-Hib response. In countries where DTwP vaccine available for use in the EPI program is manufactured by a local or other developing country manufacturer, mixing it with lyophilised Act-Hib is a reasonable option though the immunogenicity may have to be documented before routine use. However, use of TetrAct-Hib combination vaccine would be preferable in view of its lower reactogenicity and superior immunogenicity with respect to diphtheria and tetanus.

Safety, tolerability and immunogenicity of low dose Haemophilus influenzae type b conjugated to the outer membrane protein complex of Neisseria meningitidis group B

Infants vaccinated with three doses followed by a booster of either 1.0 microg of Haemophilus influenzae type b conjugated to the outer membrane protein complex of Neisseria meningitidis group B or H. influenzae 10-microg oligosaccharide vaccine conjugated to 25 microg mutant toxin (CRM197) isolated from Corynebacterium diphtheriae had protective antipolyribosylribitol phosphate concentrations.

Safety and reactogenicity of a novel DTPa-HBV-IPV combined vaccine given along with commercial Hib vaccines in comparison with separate concomitant administration of DTPa, Hib, and OPV vaccines in infants

OBJECTIVE

Combination vaccines simplify vaccine administration and have the potential to promote compliance and cost-effectiveness by decreasing the number of injections needed to immunize a child. The objective of this study was to assess the safety and reactogenicity of the diphtheria-tetanus toxoid-acellular pertussis-hepatitis B virus-inactivated polio virus (DTPa-HBV-IPV) vaccine when coadministered with different Haemophilus influenzae type B (Hib) vaccines in comparison with separate, commercially available, control vaccines in a 3-dose primary vaccination series.

METHODS

An open-label, randomized, parallel-group study in 5318 infants who were 8 to 16 weeks of age at enrollment was conducted in 90 centers in Germany. The incidence of adverse events that occurred in infants who received the DTPa-HBV-IPV candidate vaccine coadministered with 1 of 4 different Hib vaccines (given in separate sites; groups 1-4) was compared with the incidence that occurred in infants who received commercially available control vaccines (DTPa, Hib, and oral polio virus [OPV] vaccine; group 5) administered separately. The vaccines were given as a 3-dose primary series at 3, 4, and 5 months of age. Infants were assessed for solicited local and general adverse events for 4 days and for unsolicited adverse events for 30 days after each vaccine dose. The primary endpoint was to rule out a 7.5% increase in infants who experienced grade 3 (defined as preventing normal everyday activities unless otherwise specified) solicited local and general adverse events over the 3-dose primary course after the combined DTPa-HBV-IPV vaccine coadministered with Hib as compared with commercially available vaccines.

RESULTS

During the 3-dose primary course, 490 of 3029 infants (16.2%) in the pooled DTPa-HBV-IPV vaccine groups and 151 of 744 (20.3%) in the control vaccine group experienced a grade 3 adverse event (rate difference [control minus combination] 4.1%; 90% confidence interval, 1.41-7.13). The lower limit of the 90% confidence interval of the observed difference remained above the prespecified -7.5% limit for noninferiority, thereby meeting the primary endpoint. The incidences of local injection-site reactions were similar for the DTPa-HBV-IPV and DTPa injection sites. Significant differences in the incidence of both local and general adverse events were observed depending on which of the Hib vaccines was coadministered. Infants who received Hib N meningitidis outer-membrane complex protein conjugate vaccine had greater incidences of fever and, to a lesser extent, greater reactions at the Hib injection site than did infants who received other Hib vaccines.

CONCLUSIONS

The combination DTPa-HBV-IPV vaccine administered concomitantly with Hib vaccine at separate sites was at least as safe as coadministration of individual DTPa, Hib, and OPV vaccines in terms of the defined endpoints for safety.

DTPw-HB and Hib primary and booster vaccination: combined versus separate administration to Latin American children

This multicentre study was designed to establish the reactogenicity and immunogenicity profiles of primary and booster vaccination with diphtheria, tetanus, and pertussis whole-cell-hepatitis B/Haemophilus influenzae type-b (DTPw-HB/Hib) administered as either a syringe mix or as separate injections in 400 Latin American children. Both vaccine regimens were equally well tolerated and elicited post-primary excellent seropositivity rates at or close to 100% for all five component antigens. With regard to HB, 100% of subjects in the combined vaccination group, and 98.8% subjects in the separate injection vaccination group reached seroprotective antibody concentrations (>or=10 mIU/ml) 1 month after the primary vaccination course. Equally high anti-PRP antibody concentrations were reached 1 month after vaccination, with 100% of seroprotected subjects in the combined vaccination group (antibody concentrations >or=0.15 microg/ml), against 99.4% in the separate injection vaccination group. Seroprotective anti-HBs and anti-PRP antibody concentration levels persisted approximately 1 year after the primary vaccination course, just prior to booster vaccination. Finally, a significant increase of all antibody concentrations could be observed after the booster vaccination, since all but one subject in the separate injection vaccination group had protective levels of anti-HBs and anti-PRP antibodies 1 month after the booster dose. These results suggest that the combination of DTPw-HB and Hib vaccines provides an effective means for increasing vaccine coverage in childhood vaccination programmes.

Haemophilus influenzae type b conjugate vaccine diluted tenfold in diphtheria-tetanus-whole cell pertussis vaccine: a randomized trial

BACKGROUND

Despite their proven efficacy Haemophilus influenzae type b (Hib) conjugate vaccines are not given to most children in the developing world in the face of an estimated global Hib disease burden of nearly 2 million cases per annum. A major barrier to the introduction of the vaccine would be overcome by diluting the vaccine 10-fold in diphtheria-tetanus-whole cell pertussis (DTP). We report a randomized trial comparing the use of Hib conjugate vaccine diluted in a multidose vial of DTP with that of the full Hib dose.

METHODS

We randomized 168 infants to receive either the full dose Hib polysaccharide-tetanus toxoid conjugate (PRP-T) vaccine or a 1/10 dilution prepared by reconstituting the full dose in a 10-dose DTP vial. Infants were vaccinated at 6, 10 and 14 weeks of age and received a full dose as a test of immunologic memory at 9 months of age. Sera were collected at each visit and at 1 week after the booster dose. Serum anti-capsular PRP antibody concentrations were measured by enzyme-linked immunosorbent assay.

RESULTS

After the primary vaccination series, 95% of infants in the full dose arm and 94% of infants in the 1/10 dose arm achieved anti-PRP IgG antibody concentrations of > or = 1.0 microg/ml. Infants receiving the diluted vaccine had significantly higher titers of anti-PRP antibody in response to the booster dose (151.36 microg/ml vs. 68.55 microg/ml, P = 0.009).

CONCLUSIONS

The 1/10 dose of PRP-T was as immunogenic and safe as the full dose. The technique of diluting a single dose of PRP-T in a 10-dose DTP vial could potentially allow the widespread introduction of Hib vaccine in resource-poor countries currently unable to afford full dose Hib conjugate vaccine.

Safety and immunogenicity of TETRActHIB (a vaccine combining DTP vaccine and Haemophilus influenzae type B conjugate vaccine) administered to infants at 6, 10 and 14 weeks of age

The safety and immunogenicity of TETRActHIB (a vaccine combining diphtheria and tetanus toxoids-pertussis vaccine (DTP) with Haemophilus influenzae type b (Hib) conjugate vaccine (polyribosyl ribitol phosphate conjugated to tetanus protein) (PRP-T)) was assessed in 131 Cape Town infants immunized at 6, 10 and 14 weeks of age. Serological responses to all component antigens were measured before the first dose and at 18 weeks of age. In addition, anti-PRP antibodies were measured at 9 and 18 months of age to determine long-term immunogenicity. The vaccine was well tolerated by infants and no significant side-effects were reported. Responses to Hib at 18 weeks of age were good in that most infants achieved a level of anti-PRP antibodies > or = 0.15 microgram/ml, indicative of short-term protection, and 70% achieved a level > or = 1 microgram/ml, indicative of long-term protection. The proportions of children with protective levels > or = 0.15 microgram/ml and > or = 1 microgram/ml were similar at 9 and 18 months of age, i.e. approximately 75% and 45%, respectively. Responses to tetanus and diphtheria toxoids were excellent and all infants achieved protective serological levels. Responses to pertussis were moderate in that approximately 65% achieved 'protective' serum levels of pertussis agglutinins, i.e. titres > or = 320. In conclusion, this study has shown that the DTP/PRP-T vaccine is safe, immunogenic and well tolerated in infants immunised at 6, 10 and 14 weeks of age. TETRActHIB is therefore suitable for inclusion in the World Health Organisation Expanded Programme on Immunisation (WHO EPI) schedule.

Safety and antibody persistence following Haemophilus influenzae type b conjugate or pneumococcal polysaccharide vaccines given before pregnancy in women of childbearing age and their infants

BACKGROUND

Immunization of healthy women before pregnancy is a potential approach to providing increased levels of maternal antibody to newborns to protect them from infections occurring during the perinatal period and first months of life.

METHODS

Healthy nonpregnant Pima Indian women of childbearing age were randomized to receive one of two Haemophilus influenzae type b (Hib) conjugate vaccines [HbOC or Hib-meningococcal outer membrane protein complex (OMP)] or a 23-valent pneumococcal polysaccharide vaccine (PnPs). Infants received Hib-OMP vaccine at 2, 4 and 12 months of age. Vaccine safety and immunogenicity was evaluated in the women and their infants.

RESULTS

Anti-polyribose ribitol phosphate antibody titers were significantly higher in women in both Hib conjugate vaccine groups than in the pneumococcal vaccine group throughout the 37-month observation period. Antibody responses to HbOC vaccine were significantly higher than those to Hib-OMP. A subsequent booster dose of each Hib conjugate vaccine induced reactions and antibody responses similar to those of the first dose. Infants born to mothers immunized with Hib vaccines compared with PnPs had significantly higher polyribose ribitol phosphate-specific IgG antibody titers at birth and 2 months of age but lower antibody responses to Hib-OMP at 6 months and similar titers before and after boosting with Hib-OMP at 1 year of age. By contrast women immunized with PnPs did not have significantly elevated concentrations of pneumococcal-specific antibody at delivery, and their infants had pneumococcal antibody titers similar to those of infants born to mothers who did not receive pneumococcal vaccine before pregnancy.

CONCLUSION

Hib conjugate vaccine given to women before pregnancy significantly increased the proportion of infants who had protective Hib antibody levels at birth and 2 months of age.

Antibody responses of healthy infants to concurrent administration of a bivalent haemophilus influenzae type b-hepatitis B vaccine with diphtheria-tetanus-pertussis, polio and measles-mumps-rubella vaccines

OBJECTIVE

To confirm that children given a bivalent Haemophilus influenzae type b-hepatitis B vaccine (bivalent Hib-HB vaccine; COMVAX) concurrently with priming doses of diphtheria-tetanus-pertussis vaccine (DTP), a booster dose of diphtheria-tetanus-acellular pertussis vaccine (DTaP), inactivated or oral polio vaccine (IPV or OPV) and measles-mumps-rubella vaccine (M-M-R(II)) have satisfactory antibody responses to all antigens.

DESIGN

126 healthy 2-month-old infants were scheduled to receive bivalent Hib-HB vaccine concurrently with DTP (2 and 4 months of age), OPV or IPV (random allocation to OPV or IPV at 2 months of age; OPV at 4 and 14 to 15 months of age), DTaP and M-M-R(II) (14 to 15 months of age). A response was judged "adequate" if the lower bound of the 95% confidence interval on the proportion of vaccinees having a critical antibody level was <10 percentage points below prediction.

RESULTS

Antibodies to hepatitis B virus surface antigen, H. influenzae polysaccharide, diphtheria toxin, tetanus toxin, pertussis agglutinogens, pertussis toxin (as measured by enzyme immunoassay but not by Chinese hamster ovary cell assay), pertussis filamentous haemagglutinin after a booster dose of DTaP, poliovirus type 2, measles virus, and mumps virus all equalled or exceeded expected levels. Antibodies to rubella virus and pertussis filamentous haemagglutinin (after priming doses of DTP) fell slightly, and in the case of rubella significantly, below predicted levels. Antibodies to poliovirus types 1 and 3 were also below expectation after 2 doses of polio vaccine but were adequate following a third dose of vaccine.

CONCLUSION

Concurrent administration of bivalent Hib-HB vaccine with priming doses of DTP, a booster dose of DTaP, OPV, IPV, or M-M-R(II) was well tolerated and, with the possible exception of rubella, did not substantially impair the antibody response to any antigen.

Data mining in the US Vaccine Adverse Event Reporting System (VAERS): early detection of intussusception and other events after rotavirus vaccination

The Vaccine Adverse Event Reporting System (VAERS) is the US passive surveillance system monitoring vaccine safety. A major limitation of VAERS is the lack of denominator data (number of doses of administered vaccine), an element necessary for calculating reporting rates. Empirical Bayesian data mining, a data analysis method, utilizes the number of events reported for each vaccine and statistically screens the database for higher than expected vaccine-event combinations signaling a potential vaccine-associated event. This is the first study of data mining in VAERS designed to test the utility of this method to detect retrospectively a known side effect of vaccination-intussusception following rotavirus (RV) vaccine. From October 1998 to December 1999, 112 cases of intussusception were reported. The data mining method was able to detect a signal for RV-intussusception in February 1999 when only four cases were reported. These results demonstrate the utility of data mining to detect significant vaccine-associated events at early date. Data mining appears to be an efficient and effective computer-based program that may enhance early detection of adverse events in passive surveillance systems.

Immunogenicity and reactogenicity of diphtheria, tetanus and pertussis toxoids combined with inactivated polio vaccine, when administered concomitantly with or as a diluent for a Hib conjugate vaccine

In an open trial, 400 infants were randomized to vaccination with a combined diphtheria-tetanus-pertussis-inactivated polio vaccine (DTaP-IPV) either mixed with a Haemophilus influenzae type b (Hib) tetanus toxoid conjugate immediately before injection (DTaP-IPV/Hib (mix)) or given concurrently with the Hib conjugate at separate injection sites (DTaP-IPV+Hib (sep)). The pertussis component consisted of pertussis toxoid alone. The vaccines were given intramuscularly at 3, 5 and 12 months of age. No vaccine-related serious adverse events occurred. Local reactions were evaluated from diary cards completed by the parents. Infants who received DTaP-IPV/Hib (mix) experienced fewer local reactions. Sera were obtained 28-45 days after the second and third vaccinations. Total Hib capsular antibodies were similar in the two groups after the second injection but lower in the group receiving DTaP-IPV/Hib (mix) than in the group receiving DTaP-IPV+Hib (sep) after the third injection (geometric mean 6.1 vs 10.4 microg/ml). Mixing of the vaccines also led to somewhat lower diphtheria toxin antibodies (5.9 vs. 7.7 IU/ml after the third injection) while tetanus antibodies were higher (3.9 vs. 2.5 IU/ml after the third injection). Antibodies against pertussis toxin and the three polio virus types were similar in the two groups. The moderate impairment of the Hib antibody response caused by mixing of the Hib conjugate with aluminium adsorbed DTaP may be due to physicochemical interference but is probably of little clinical importance because of the ability of the Hib conjugates to induce an immunologic memory.

Adverse events following vaccination in premature infants

The aims of this study were to study the frequency, severity and types of adverse reactions following DPT/Hib (diphtheria and tetanus toxoids and pertussis/Haemophilus influenzae type B conjugate) immunization in very preterm infants and to identify possible risk factors. Case notes of 45 preterm babies vaccinated in the neonatal intensive care unit between January 1993 and December 1998 were studied retrospectively. Birthweight, gestational age, duration of ventilation, oxygen dependency, timing of vaccination, weight, corrected gestation at vaccination and apparent adverse effects were noted. Apparent adverse events were noted in 17 of 45 (37.8%) babies: 9 (20%) had major events, i.e. apnoea, bradycardia or desaturations, and 8 (17.8%) had minor events, i.e. increased oxygen requirements, temperature instability, poor handling and feed intolerance. Babies with major events were significantly younger (p < 0.05), had a lower postmenstrual age (p < 0.05) and weighed less (p < 0.05) at the time of vaccination compared with babies without major events. No differences in the mean birthweight, gestational age, duration of ventilation or oxygen dependency were found between the two groups. Age at vaccination of 70 days or less was significantly associated with increased risk (p < 0.01). Of 27 babies vaccinated at 70 days or less, 9 (33.3%) developed major events compared with none when vaccinated over 70 d.

CONCLUSION

Vaccine-related cardiorespiratory events are relatively common in preterm babies. Problems were much more common if vaccine is administered at or before 70 d. These babies should therefore be monitored postvaccination. Further prospective studies are needed to clarify whether delaying vaccination offers protection against these adverse events.

Sudden unexpected death in infants under 3 months of age and vaccination status- -a case-control study

AIMS

To determine whether DTPP+Hib vaccination (diphtheria, tetanus, pertussis, poliomyelitis +/- haemophilus) increased the risk of sudden unexpected death (SUD) in children under 3 months of age.

METHODS

We conducted a multicentre case-control study in the 28 French 'SIDS Centers'. Case selection was based on death labelled sudden infant death syndrome (SIDS) of an infant aged between 30 and 90 days. Three living controls were selected, matched for sex, gestational age and born immediately after the victim in the same maternity unit.

RESULTS

We identified 114 cases of SUD aged between 30 and 90 days and 341 live controls matched for age and sex and born in the same maternity unit as the case. DTPP+/-Hib immunization did not increase the risk of SUD (OR 1.08) (95% CI 0.49, 2.36) in children under 3 months of age when adjusted for sleeping position, illness in the week before death, maternal tobacco consumption, birth weight, type of mattress, breastfeeding and sex. However, low birth-weight (6.53 [2.29, 18.9]), multiple birth (5.1 [1.76, 15.13]), no breastfeeding (1.77 [1.1, 2.85]), prone sleeping position (9.8 [5, 8, 18, 9]), soft mattress (3.26 [1.69, 6.29]), recent illness (3.44 [1.84, 6.41]) and parental smoking (1.74 [1.2, 2.96]) were confirmed as risk factors in early SIDS.

CONCLUSIONS

DTPP+/-Hib immunization is not a risk factor for early SUD. In this population, we found the same risk factors as described for SIDS.

A combined liquid Hib (PRP-OMPC), hepatitis B, diphtheria, tetanus and whole-cell pertussis vaccine: controlled studies of immunogenicity and reactogenicity

We evaluated the immunogenicity and reactogenicity of a new liquid pentavalent combination vaccine, which incorporates a diphtheria, tetanus and whole-cell pertussis vaccine (DTP) with Hib (PRP-OMPC) and hepatitis B vaccine (HB), in a series of three studies involving 2156 infants. The vaccination schedule was 2, 4, 6 and 18 months for all studies. In addition, subjects in the third study also received a dose of monovalent hepatitis B vaccine at birth. The principal study was a randomised double blind trial of two separate, but concurrently administered vaccines in each of three groups: pentavalent vaccine [DTP-Hib-HB] plus placebo (Group A, n=619); quadrivalent vaccine [DTP-HB] plus Hib vaccine (Group B, n=620); and bivalent vaccine [Hib-HB] plus DTP (Group C, n=226). The second study (Group D, n=231) was an open trial of three separate, but concurrently administered licensed control vaccines (DTP, Hib and HB). The third study (Group E, n=460) administered a dose of monovalent hepatitis B vaccine at birth followed by pentavalent vaccine as for Group A. Subjects were bled prior to the 2- and 18-month vaccinations, and a month after the 6- and 18-month vaccinations. A diary card was used to record subject temperatures and other systemic and local clinical signs for 7 days after each vaccination. The pentavalent vaccine, whether or not preceded by a birth dose of hepatitis B vaccine, was generally well tolerated at all administration times, and had a reactogenicity profile similar to that observed for licensed vaccine controls. Diphtheria and tetanus antibody levels were substantially above protective levels in all study groups. The anti-HBs responses (% > or = 10 mIU/ml) following the 6-month dose of vaccines were, respectively, for Groups A-E: 83.2, 91.7, 96.5, 98.8 and 93.9%, and following the 18-month doses: 87.9, 97.5, 98.8, 98.8 and 92.8%. Anti-PRP responses (% > or = 1.0 microg/ml) following the 6-month dose for Groups A-D were 86.0, 90.5, 91.2, and 74.4%, and after the 18-month dose for Groups A-E were 97.3, 98.3, 98.1, 97.0, and 99.5%. Consistently higher geometric mean titres (GMTs) for pertussis antibodies to agglutinogens (Agg2, Agg3) and pertactin were recorded for the pentavalent vaccine compared to the licensed control vaccine, though they were somewhat lower for pertussigen (PT). Except for the hepatitis B response, antibody responses induced by the pentavalent vaccine to all antigens with a schedule commencing at 2 months of age and completed at 18 months were equivalent to responses to the same antigens induced by the separate, but concurrently administered licensed control vaccines. A regimen of a birth dose of hepatitis B vaccine followed by pentavalent vaccine at 2, 4, 6 and 18 months was not countered by any clinically significant decrease in seroresponses.

Antibody responses to pneumococcal and haemophilus vaccinations in patients with B-cell chronic lymphocytic leukaemia

Although vaccination against Streptococcus pneumoniae (S. pneumoniae) and Haemophilus influenzae type b (Hib) is recommended for immunocompromised patients, such as patients with B-cell chronic lymphocytic leukaemia (B-CLL), its protective effect is questionable. We studied antibody responses to pneumococcal polysaccharide vaccine (Pneumovax-23) and to conjugated H. influenzae type b-vaccine (Act-Hib) in 25 patients with B-CLL. After vaccination, the number of patients with antibody levels in the protective range against pneumococcal serotypes and H. influenzae b increased from 9 (38%) to 12 (50%) of 24 patients and from 8 (35%) to 11 (48%) of 23 patients, respectively. The patients with adequate antibody response to Pneumovax-23 and Act-Hib had significantly less advanced stages of B-CLL, higher gammaglobulin levels, total IgG-levels and IgG-subclasses 2 and 4 levels, and lower levels of soluble CD23. Consequently, vaccination with these vaccines should be given as soon as the diagnosis of B-CLL is made, early in the course of the disease with determination of post-vaccination antibody levels.

Safety and immunogenicity of combined or associated administration of PRP-T vaccine with diphtheria, tetanus and pertussis vaccine in Thai children

To assess whether the combination of a diphtheria, tetanus and pertussis vaccine with a Haemophilus influenzae type b conjugate vaccine (PRP-T) had any effect on immunogenicity or safety compared with separate administration of the vaccines, 158 infants were randomized to receive the vaccines either in association or as a combination at 2, 4, and 6 months of age. A total of 126 infants (59 associated, 67 combination) completed the three-dose regimen and were analysed for immunogenicity and safety. With respect to safety, there were no significant differences between the two groups. The combination vaccine was well tolerated with adverse reactions consisting mainly of transient pain, redness, induration and some low-grade fever. With respect to immunogenicity, response to PRP-T vaccine was good. Following just two doses, all infants achieved anti-PRP titers >0.15 microg/ml, regardless of whether the vaccine was given in combination or association. Following three doses, 98.5 per cent of infants in the combination group and 98.3 per cent in the association group had titers higher than 1.0 microg/ml.

Tetracel (American Home Products)

American Home Products (AHP) is developing Tetracel as a vaccine for children (aged 12 to 18 months) against diphtheria, tetanus, pertussis and Haemophilus influenzae type B (Hib) [275146]. The components are contained in AHP's two currently marketed vaccines. ACEL-Immune contains diphtheria and tetanus toxoids with acellular pertussis vaccine adsorbed, and HibTITER contains the Haemophilus influenzae B conjugate vaccine (diphtheria CRM197 protein conjugate) [239655]. As of January 2000, Lehman Brothers predicted Tetracel to be approved in the US during 2000 [354434].

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.