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Pharmacology: Pharmacodynamics: Immune response: The following immune responses were observed across studies one month post vaccination with Boostrix Polio in children, adolescents and adults (Table 1). (See Table 1.)
Click on icon to see table/diagram/imageAs with other adult-type Td vaccines, Boostrix Polio induces higher seroprotection rates and higher titres of both anti-D and anti-T antibodies in children and adolescents as compared to adults.
Efficacy in protecting against pertussis: The pertussis antigens contained in Boostrix Polio are an integral part of the paediatric acellular pertussis combination vaccine (Infanrix), for which efficacy after primary vaccination has been demonstrated in a household contact efficacy study. The antibody titres to all 3 pertussis components following vaccination with Boostrix Polio are at least as high or higher than those observed during the household contact efficacy trial. Based on these comparisons, Boostrix Polio would provide protection against pertussis, however, the degree and duration of protection afforded by the vaccine are undetermined.
Passive protection against pertussis in infants (below 3 months of age) born to mothers vaccinated during pregnancy: In a randomised, cross-over, placebo-controlled study, higher pertussis antibody concentrations were demonstrated at delivery in the cord blood of babies born to mothers vaccinated with Boostrix (N=291) versus placebo (N=292) during the third trimester of pregnancy. The concentrations of antibodies against the pertussis antigens PT, FHA and PRN were respectively 8, 16 and 21 times higher in the cord blood of babies born to vaccinated mothers versus controls. These antibody titres may provide passive protection against pertussis, as shown by observational effectiveness studies.
Immunogenicity in infants and toddlers born to mothers vaccinated during pregnancy: In follow-up trials in more than 500 infants and toddlers born to vaccinated mothers, clinical data did not show clinically relevant interference between maternal vaccination with Boostrix and the infant and toddler response to diphtheria, tetanus, hepatitis B, inactivated polio virus, Haemophilus influenzae type b or pneumococcal antigens. Although lower concentrations of antibodies against some pertussis antigens were observed post primary and post booster vaccination, 92.1-98.1% of subjects born to vaccinated mothers showed a booster response against all pertussis antigens. Current epidemiological data on pertussis disease do not suggest any clinical relevance of this immune interference.
Effectiveness in the protection against pertussis disease in infants born to women vaccinated during pregnancy: Boostrix or Boostrix Polio vaccine effectiveness (VE) was evaluated in three observational studies, in UK, Spain and Australia. The vaccine was used during the third trimester of pregnancy to protect infants below 3 months of age against pertussis disease, as part of a maternal vaccination programme.
Details of each study design and results are provided in the Table 2. (See Table 2.)
Click on icon to see table/diagram/imageIf maternal vaccination occurs within two weeks before delivery, vaccine effectiveness in the infant may be lower than the figures in the table.
Persistence of the immune response: Five years following vaccination with Boostrix Polio, at least 89.4% of children from the age of 4 to 8 years were seroprotected or seropositive against all vaccine components, except for the pertussis toxoid component (40.9% of subjects were seropositive against pertussis toxoid). Ten years following vaccination with Boostrix Polio, at least 78.7% of adults and adolescents were seroprotected or seropositive against all vaccine components.
Immune response after a repeat dose of Boostrix Polio: The immunogenicity of Boostrix Polio, administered 5 years after a previous booster dose of Boostrix Polio at 4 to 8 years of age, has been evaluated. One month post vaccination, > 99 % of subjects were seropositive against pertussis and seroprotected against diphtheria, tetanus and all three polio types.
In adults, one dose of Boostrix Polio administered 10 years after the previous dose, elicited a protective immune response in > 96.8% of the subjects (for the diphtheria antigen) and in 100% of the subjects (for the tetanus and polio antigens). The booster response against the pertussis antigens was between 74.2 and 98.4%.
Immune response in subjects without prior or with unknown vaccination history: In adolescents aged from 11 to 18 years, without previous pertussis vaccination and no vaccination against diphtheria and tetanus in the previous 5 years, one dose of Boostrix (dTpa component of Boostrix Polio) induced an antibody response against pertussis and all subjects were protected against tetanus and diphtheria.
In subjects ≥ 40 years of age that had not received any diphtheria or tetanus containing vaccine in the past 20 years (including those who have never been vaccinated or whose vaccination status was unknown), one dose of Boostrix Polio induced an antibody response against pertussis and protected against tetanus and diphtheria in the majority of cases.
Toxicology: Pre-clinical Safety Data: Animal toxicology and/or pharmacology: Pre-clinical data reveal no special hazard for humans based on conventional studies of safety and of toxicity.
