Abstract
BackgroundAlthough a combined Haemophilus influenzae type b (Hib)/meningococcal capsular group C (MenC) conjugate vaccine with a tetanus toxoid carrier protein (Hib/MenC-TT) is not licensed for use in those above 2 years of age due to lack of data on safety and efficacy, certain patient groups at high risk of MenC and/or Hib disease are recommended to receive it. Laboratory workers working with Hib and/or MenC cultures may be at a potentially increased risk of acquiring infectious diseases and vaccination is therefore an important safety consideration. We undertook a clinical trial to investigate the safety and immunogenicity of Hib/MenC-TT vaccine in this cohort.MethodsA total of 33 subjects were recruited to the trial, all of whom were vaccinated. Serology was completed on samples taken at baseline and four weeks following vaccination to determine MenC specific IgG, MenC serum bactericidal antibody (SBA), anti-Hib polyribosylribitol phosphate (PRP) IgG and anti-tetanus toxoid IgG responses.ResultsAt baseline, high proportions of subjects had protective antibody concentrations against MenC, Hib and tetanus due to previous vaccination and/or natural exposure. Vaccination induced > 3, 10 and 220 fold increases in geometric mean concentrations for MenC SBA, anti-tetanus toxoid IgG and anti-Hib PRP IgG, respectively. Following vaccination, 97% of subjects had putative protective SBA titres ≥ 8, 100% had short term protective anti-Hib PRP IgG concentrations ≥ 0.15 μg/mL and 97% had protective anti-tetanus toxoid concentrations ≥ 0.1 IU/mL. No safety concerns were reported with minor local reactions being reported by 21% of subjects.ConclusionsImmunological responses determined in this trial are likely a combination of primary and secondary responses due to previous vaccination and natural exposure. Subjects were a representative cross-section of laboratory workers, enabling us to conclude that a single dose of Hib/MenC-TT was safe and immunogenic in healthy adults providing the evidence that this vaccine may be used for providing protection in an occupational setting.
Highlights
A combined Haemophilus influenzae type b (Hib)/meningococcal capsular group C (MenC) conjugate vaccine with a tetanus toxoid carrier protein (Hib/meningitidis capsular group C (MenC)-TT) is not licensed for use in those above 2 years of age due to lack of data on safety and efficacy, certain patient groups at high risk of MenC and/or Hib disease are recommended to receive it
Study population and schedule Enrolment into this single dose Hib/MenC-TT vaccine trial was open to adult (≥18 years of age) laboratory staff from the Manchester Medical Microbiology Partnership (MMMP) who were considered to be at potential occupational exposure to Hib and/or MenC
In conclusion, Hib/MenC-TT when administered as a single dose to healthy adults is safe and immunogenic
Summary
A combined Haemophilus influenzae type b (Hib)/meningococcal capsular group C (MenC) conjugate vaccine with a tetanus toxoid carrier protein (Hib/MenC-TT) is not licensed for use in those above 2 years of age due to lack of data on safety and efficacy, certain patient groups at high risk of MenC and/or Hib disease are recommended to receive it. Laboratory workers working with Hib and/or MenC cultures may be at a potentially increased risk of acquiring infectious diseases and vaccination is an important safety consideration. The Hib vaccine was extremely effective in the targeted age group reducing invasive disease in England and Wales from almost 500 cases per year to 20 cases, two years following implementation [1]. The MenC vaccine was successful and reduced disease incidence by 86.7% in the targeted age groups, within two years of implementation [3]. Use of live cultures is not restricted to clinical and reference laboratories as there are many additional laboratories undertaking research This results in a significant population of laboratory workers with a potential exposure risk including those undertaking functional immunoassays such as the MenC and Hib serum bactericidal antibody (SBA) assay to evaluate vaccine responses
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