Immunogenicity of a five-component acellular pertussis vaccine in infants and young children

Prevention of pertussis across the age spectrum through the use of the combination vaccines PENTACEL™ and ADACEL™

Acellular pertussis-containing combination vaccines are widely used in the developed world for the control of pertussis and have been successful in controlling disease in preschool-aged children. Combination vaccines formulated for use in adolescents and adults have been developed more recently and are increasingly being implemented for the control of pertussis in these age groups. One such family of products is PENTACEL (Haemophilus influenzae type b conjugate vaccine reconstituted with component pertussis vaccine and diphtheria and tetanus toxoids adsorbed combined with inactivated poliomyelitis vaccine, DTaP-IPV-Hib), for use in young children, and ADACEL (tetanus and diphtheria toxoids adsorbed combined with component pertussis vaccine, dTap) for use in adolescents and adults. These products have been demonstrated to be safe, immunogenic and effective for the control of pertussis and the other included diseases.

Which strategy for pertussis vaccination today?

Pertussis (whooping cough) remains an epidemic disease responsible for infant and child morbidity and mortality, and is perceived as a serious public health problem. Since the widespread use of whole-cell pertussis vaccines in the 1940s, vaccination programs have varied greatly between countries. National specificity is a function of several factors. The most important are: vaccine efficacy and tolerability;vaccine coverage and distribution; and vaccine acceptance by parents and professionals. During the 1970s, Sweden, England, Wales and Japan provided contrasting examples of the attitude of health authorities to the use of whole-cell vaccines. The increase in pertussis incidence was noted as a consequence of active opposition to this vaccine. The re-emergence of pertussis in the 1990s, in countries with high vaccination coverage and increased incidence of disease in individuals >15 years and <6 months of age, has drawn attention to the role of booster doses of pertussis vaccines and their introduction into regular vaccination programs. The use of acellular vaccines for booster doses for adolescents and adults would seem unambiguous because of their decreased reactogenicity, although the exact schedule has yet to be established. The choice between the two kinds of vaccines is more difficult for primary courses, where safety and efficacy profiles are similar, and the attitude towards acellular vaccines varies from country to country. In this case, the strategy adopted results from the national history of pertussis infection and from the quality of the available whole-cell vaccine. Two contrasting examples are the US, where acellular vaccines were licensed for the primary series in the 1990s, and the UK, where whole-cell vaccines are exclusively used for primary immunization. The changing epidemiology of pertussis, and its local diversification, would suggest that at present it is difficult to define a single worldwide strategy with only one kind of vaccine and one schedule. In order to control pertussis incidence, each country should continue to determine the best national vaccination program established in very close relation to the past and present epidemiological situation and available healthcare resources.

Long-term pertussis-specific immunity after primary vaccination with a combined diphtheria, tetanus, tricomponent acellular pertussis, and hepatitis B vaccine in comparison with that after natural infection

The aim of this study was to compare pertussis-specific humoral and cellular immunity in children 5 years after a primary vaccination with a combined diphtheria, tetanus, tricomponent acellular pertussis, and hepatitis B vaccine (DTaP-HBV; InfanrixHepB; SmithKline Beecham) with immunity after natural infection. The subjects were 38 children aged 5 to 6 years who received DTaP-HBV at 3, 5, and 11 months of life and 21 subjects of similar ages and sex who acquired pertussis in the first year of life. Immunoglobulin G (IgG) antibody titers against Bordetella pertussis antigens, peripheral blood mononuclear cell-specific proliferation, and the secretion of cytokines were evaluated. After 5 years, only a small proportion of vaccinated and infected children had significant specific concentrations of IgG in serum against all three B. pertussis antigens, and T-cell responses persisted in a minority of subjects. A preferential type 1 cytokine response with the secretion of gamma interferon was observed in the pertussis group, whereas a type 2 skewed response was observed in the vaccinated children; however, the quantitative differences in the cytokines produced by DTaP-HBV and natural infection were minimal. In conclusion, our results show that the immune responses induced by primary pertussis vaccination are qualitatively and quantitatively similar to those seen in children who recovered from natural infection and highlight the need for booster immunization with pertussis vaccines in order to maintain adequate levels of a specific immune response to B. pertussis.

Effectiveness of a single dose of acellular pertussis vaccine to prevent pertussis in children primed with pertussis whole cell vaccine

We estimated the protection given by one booster dose of acellular pertussis vaccine (aP) given at 18 months or before school entry to children already primed with whole cell vaccine (wP). Case-control studies were conducted in these two age groups. In children who received or were eligible to receive their 18 months booster, the risk of pertussis was 1.4 and 3.6 times higher for those with 4 and 3 wP, respectively, compared to those with 3 wP + 1 aP. In 5 and 6 yr old children, the risk of pertussis among the subjects with 5 and 4 wP, was 1.4 and 2.1 times higher respectively than in those who received 4 wP + 1 aP. A single dose of aP increased the protection against pertussis and this protection was greater than that obtained with a wP booster.

Comparison of a fifth dose of a five-component acellular or a whole cell pertussis vaccine in children four to six years of age

BACKGROUND AND OBJECTIVES

Acellular pertussis vaccines are now preferred for all five childhood immunization doses; however, there are few data on the safety and immunogenicity of five consecutive doses. This study compared a fifth dose of an acellular and a whole cell pertussis vaccine in 4- to 6-year-old children previously immunized with four doses of acellular or whole cell pertussis vaccine.

STUDY DESIGN

In a double blind, multicenter study, 366 healthy children were randomly allocated to receive a single injection of a 5-component acellular or a whole cell pertussis vaccine, each combined with diphtheria and tetanus toxoids and inactivated poliovirus vaccine.

RESULTS

Although injection site redness > or =50 mm and swelling > or =50 mm were common in children who had received five doses of acellular (50% and 48.1%, respectively) or whole cell (66.2% and 59.7%) pertussis vaccine, limb soreness and limitation of motion were less frequently reported after acellular (1.9% and 0%) than after whole cell (49.2% and 36.3%; P < 0.0001) pertussis vaccine. Pre-fifth dose antipertussis antibody titers were higher in children who previously had received four doses of acellular pertussis vaccine. Postimmunization antibody titers against pertussis toxin, filamentous hemagglutinin, pertactin and tetanus toxin were higher in recipients of five doses of acellular pertussis vaccine, whereas antibody titers to diphtheria toxin, pertussis fimbriae and poliovirus serotypes were higher in recipients of five doses of the whole cell pertussis vaccine (P < 0.05 for all comparisons).

CONCLUSIONS

A regimen consisting of five doses of a five-component acellular pertussis combination vaccine is safe and immunogenic in pre-school children. Local adverse reactions are common but are less painful and activity-limiting than a regimen of five doses of a whole cell pertussis vaccine.

Correlation of clinical parameters and immunological function with human immunodeficiency virus plasma viremia in children

Studies of immune function in human immunodeficiency virus (HIV)-infected children are important, because functional abnormalities can precede CD4+ T-cell loss and are associated with the development of opportunistic and bacterial infections. We sought to correlate clinical parameters and immunological function with HIV RNA plasma levels in 20 children. HIV RNA levels were measured by a polymerase chain reaction assay. We analyzed T-cell responses to mitogens (phytohemagglutinin, concanavalin A, and pokeweed [PWM]) and antigens (tetanus toxoid and Candida albicans); T-cell suppressor activity; and humoral immunity to Haemophilus influenzae, hepatitis B, tetanus, and diphtheria vaccines. The median age of the children was 6 years. Eight children had HIV RNA levels less than 200 to 9621 copies per milliliter (group I). Four children had 37,970 to 82,630 copies per milliliter (group II). Eight children had 102,100 to 191,200 copies per milliliter (group III). There were no differences in the HIV-related complications between group I and II children. Group I/II children had significantly higher CD4+ T-cell counts (P = 0.02), less symptomatic HIV disease (P = 0.005), and more detectable protective vaccine immunity (P = 0.014) compared with group III children. Responses to mitogens were conserved in most children. Group I children tended to have higher responses to tetanus toxoid than group II children and significantly higher responses than group III children (P = 0.01). Group I had significantly higher responses to C. albicans than groups II (P = 0.016) and III (P = 0.001). Group I/II children tended to have lower suppressor activity compared with group III children (median, 0 vs 64%). We demonstrated that humoral and cellular immune dysfunction exists at all stages of disease in HIV-infected children but was most severe in children with greater than or equal to 100,000 HIV RNA copies per milliliter. Function was the most intact in children with less than 10,000 copies per milliliter.

Correlation of in vitro T-cell and B-cell function with responses to childhood vaccines in children with human immunodeficiency virus infection

We analyzed T-cell responses to mitogens and antigens and B-cell differentiation in response to T-cell dependent (TCD) and independent stimuli in 22 human immunodeficiency virus (HIV)-infected children (1 to 9 years of age) according to the presence of protective humoral immunity at a mean time of 18 months after vaccination with Haemophilus influenzae type b, hepatitis B, diphtheria, and tetanus vaccines. The 17 vaccine responders had a mean of 3.2 responses. However, their antibody levels were lower compared with healthy children. The 5 nonresponders had a mean of 0.84 responses. There were no significant differences between responders and nonresponders regarding age, Centers for Disease Control and Prevention (CDC) disease class, CDC immunologic class, serum immunoglobulin (Ig) levels, or in the use of antiretroviral therapy. However, responders tended to have higher age-adjusted absolute CD4 cell counts than nonresponders (p = 0.07). Nonetheless, there was no correlation between antibody levels and age-adjusted CD4 counts for each of the 4 TCD vaccines. Responders had conserved lymphoproliferative responses to mitogens and to candida antigen; 7 (41%) had normal responses to tetanus antigen. While nonresponders had some conserved responses to mitogens, only 1 had a response to antigen. Thirteen responders (77%) and only 1 nonresponder (20%) had normal responses to at least 2 of the 3 mitogens and 1 of the 2 antigens (p = 0.04). Although defects in B-cell differentiation were detected in both groups, they were profound and generalized in the nonresponders. Fourteen responders (82%) had at least 1 normal B-cell response compared with none of the 5 nonresponders (p = 0.002). There were no correlations between normal lymphoproliferative responses and age, CD4 counts, serum immunoglobulin G (IgG) levels, or the use of antiretroviral therapy. Immunologic function is important in the evaluation of HIV-infected children.

Safety and immunogenicity of an acellular pertussis diphtheria tetanus vaccine given as a single injection with Haemophilus influenzae b conjugate vaccine

To determine if an acellular pertussis-diphtheria-tetanus vaccine could be combined with a Haemophilus influenzae b conjugate vaccine as a single injection, we randomized 468 children between 17 and 21 months of age previously immunized with three doses of each vaccine to receive a five-component acellular pertussis vaccine combined with diphtheria and tetanus toxoids, and Haemophilus influenzae b-tetanus toxoid conjugate vaccine either as separate injections on separate days, separate injections on the same day, or as a single combined injection. Rates of adverse reactions were similar amongst the groups except for increased injection site tenderness (29.2% vs 17%, RR 1.76, 95% CI 1.09-2.85) and fussiness (36.4% vs 23.3%, RR 1.59, 95% CI 1.05-2.41) in the group given the combined injection rather than separate injections on separate days. Antibody levels against the capsular polysaccharide of H. influenzae b after the single combined injection (47.1 micrograms ml-1) were lower than after separate injections on the same day (66.0 micrograms ml-1; P < 0.05) but higher than when the injections were administered on separate days (28.4 micrograms ml-1; P < 0.001). We conclude that the five-component acellular pertussis vaccine is safe and immunogenic when combined with diphtheria and tetanus toxoids and H. influenzae b-tetanus toxoid conjugate vaccine in children receiving the fourth dose of the immunization series.

A cellular pertussis vaccine (Infanrix-DTPa; SB-3). A review of its immunogenicity, protective efficacy and tolerability in the prevention of Bordetella pertussis infection

SB-3 (Infanrix-DTPa) is one of a new generation of vaccines for immunisation against pertussis (whooping cough), diphtheria and tetanus. It is a 3-component (pertussis toxin, filamentous haemagglutinin and pertactin) chemically inactivated acellular pertussis pertussis-diphtheria-tetanus toxoid (DTaP) vaccine, and it differs from conventional whole-cell pertussis-diphtheria-tetanus toxoid (DTwP) vaccines in that it comprises inactivated purified Bordetella pertussis antigens rather than whole cells of the bacillus. SB-3, like a number of other DTaP vaccines, elicits a similar or more often, a significantly greater immune response than various DTwP vaccines in healthy infants and young children. initial data from comparative studies indicate that SB-3 also remains immunogenic when given in combination with hepatitis B vaccine or concurrently administered with Haemophilus influenzae type b (HbOC) conjugate vaccine. A combination of SB-3 and H. influenzae type b tetanus (PRP-T) conjugate vaccine results in lower anti-PRP antibody response than when both vaccines are administered concurrently. Data from two large, multicentre, German and Italian studies in infants indicate that the protective efficacy of SB-3 against pertussis was significantly better than one DTwP (DTwP-CON) but similar to another one (DTwP-BW) under investigation. Compared with another DTaP vaccine (BIO-3), SB-3 was just as protective. Overall, the data from these 2 studies indicate that primary vaccination with SB-3 provides effective protection against pertussis, even under the stringent conditions of a household contact with typical pertussis. As the other DTaP vaccines, SB-3 is better tolerated than DTwP vaccines, with a significantly lower incidence of common adverse events such as local reactions (swelling, pain and a erythema), irritability, fever, persistent crying and local tenderness. Clinical experience with SB-3 thus far indicates that, like other DTaP vaccines, it is associated with significantly fewer common (non-serious) adverse events than DTwP vaccines. Less clear is whether it has any advantage over DTwP vaccines with respect to protective efficacy or over other DTaP vaccines with respect to tolerability and protective efficacy. Nevertheless, the available data support the use of SB-3 for infant immunisation, as well as providing a suitable basis for the development of new combination vaccines.

Adverse reactions and antibody response to four doses of acellular or whole cell pertussis vaccine combined with diphtheria and tetanus toxoids in the first 19 months of life

To assess the safety, immunogenicity, and lot consistency of a five-component acellular pertussis vaccine combined with diphtheria and tetanus toxoid (Connaught Laboratories Limited), we randomly allocated 432 infants to receive one of three lots of an acellular pertussis vaccine or a single lot of whole cell pertussis vaccine. Infants were immunized at 2, 4 and 6 months of age and between 17 and 19 months of age. Local and systemic adverse reactions were reported significantly more frequently by recipients of the whole cell than acellular vaccine after each dose. The antibody response against pertussis toxin, filamentous hemagglutinin, and 69 kDa protein was of greater magnitude in acellular pertussis vaccine recipients than whole cell pertussis vaccine recipients. Small differences were detected amongst the vaccine lots tested. We conclude that the acellular pertussis vaccine is safe and immunogenic for the first four doses in children under 2 years of age.

The effect of formaldehyde, hydrogen peroxide and genetic detoxification of pertussis toxin on epitope recognition by murine monoclonal antibodies

The effect of detoxification of pertussis toxin (PT) for vaccine usage by either genetic manipulation, hydrogen peroxide or formaldehyde treatment on epitope recognition by a large collection of murine monoclonal pertussis toxin antibodies (PT MAbs) was assessed in a solid-phase and a soluble phase enzyme-linked immunosorbent assay (ELISA). The MAb binding patterns were found to be different in the two assays as the immobilization step appeared to cause conformational alterations in the native as well as the toxoided forms of PT. According to the solid-phase ELISA, genetic, hydrogen peroxide and 0.35% formaldehyde detoxification of PT resulted in reduced epitope binding in 2.9, 31.4 and 78.1% of the MAbs, respectively. In the soluble-phase ELISA, in which the MAbs were allowed to react with the toxoids or native toxin in solution, the percentages of MAbs showing decreased binding activity were 9.1, 50.0 and 71.4%, respectively. Stabilization of native PT and the genetically inactivated PT by 0.035% formaldehyde reduced the epitope binding activity in 50.0 and 8.7% of the MAbs, respectively. Increased antibody binding in the soluble-phase ELISA was observed in some of the toxoids: this ranged from 0% in the 0.35% formaldehyde-treated PT to 13.6% in the hydrogen peroxide-treated and 27.3% in the genetically detoxified PT. Regarding the effects of detoxification on epitopes recognized by PT-neutralizing MAbs in the soluble-phase ELISA, we found that treatment of PT with either 0.035%, 0.35% formaldehyde or hydrogen peroxide induced impairment of epitope binding in 72.7, 81.8 and 45.5% of the MAbs, respectively. In the genetically inactivated PT, the epitopes recognized by the neutralizing MAbs either appeared to remain intact or to show increased MAb binding activity. The epitope-binding patterns of several PT MAbs with mouse-protective properties varied considerably and were shown to be dependent on the detoxification procedure employed. The relevance of epitope alterations on PT as a vaccine component is discussed. The results of the present study may have important implications for future quality assessment of PT for use in acellular pertussis vaccines.

Safety and immunogenicity of two acellular pertussis vaccines with different pertussis toxoid and filamentous hemagglutinin content in infants 2-6 months old

The optimal composition and antigen content of acellular pertussis vaccines is not known. Two vaccines with different quantities of pertussis toxoid (10 and 20 micrograms) and filamentous hemagglutinin (5 and 20 micrograms) and identical 69 kD protein (3 micrograms) and fimbriae 2 and 3 (5 micrograms) combined with diphtheria and tetanus toxoids were compared in a randomized, double-blind study in 2,050 infants undergoing their primary immunization series at 8 centers in the US and Canada. A 6:1 increased antigen to lower antigen allocation was used; 96% of infants received 3 doses and completed the study. A 'clinically significant' local reaction was reported in 3-6% of participants after each dose. Erythema was the most common reaction occurring in 3-5% of infants after the second or third dose. A clinically significant systemic adverse reaction was reported in 28-34% of vaccinees (or vaccinated children) after each dose; fever (7-18%) and fussiness (12-17%) were most common. There were no differences in adverse events between the 2 vaccine formulations. Antibody responses were measured in 292 infants at 1 center. At 7 months, geometric mean anti-filamentous hemagglutinin antibody titers were higher in recipients of the higher antigen content vaccine (p < 0.001) whereas recipients of the lower antigen content formulation had higher anti-fimbriae antibody (p < 0.001) and agglutinin titers (p < 0.05). No differences were detected in anti-pertussis toxin or other antibody responses between the formulations. We conclude that increasing the antigen content of the acellular pertussis vaccine had a variable effect on antibody response but was not associated with increased adverse reactions.