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Matthew D Snape

Publications and source records attributed to Matthew D Snape.

4 recordsLinked to original sources
PubMed2006

Serogroup C meningococcal glycoconjugate vaccine in adolescents: persistence of bactericidal antibodies and kinetics of the immune response to a booster vaccine more than 3 years after immunization.

BACKGROUND: The persistence of protection from meningococcal disease following immunization with serogroup C meningococcal (MenC) glycoconjugate vaccines in infancy is short-lived. The duration of protective immunity afforded by these vaccines in other at-risk age groups (i.e., adolescents and young adults) is not known. We evaluated the persistence of bactericidal antibodies following immunization with a MenC glycoconjugate vaccine (MenCV) in adolescents and the kinetics of immune response to a meningococcal AC plain polysaccharide vaccine (MenPS) challenge or a repeat dose of MenCV. METHODS: We conducted a randomized comparative trial of 274 healthy 13-15-year-olds from whom a total of 4 blood samples were obtained (prior to administration of a dose of MenPS or MenCV, again on 2 further occasions at varying times from days 2-7 after vaccination, and finally on day 28 after vaccination. The correlate of protection was a serum bactericidal assay titer > or = 8 (with a serum bactericidal assay using human complement). RESULTS: A serum bactericidal assay using human complement titer > or = 8 was observed in 75% of participants at baseline (mean age, 14.5 years; mean time since routine MenCV vaccination, 3.7 years). No increase in serum bactericidal assay geometric mean titers was detected until day 5 after administration of MenPS. Geometric mean titers following administration of MenCV were significantly higher than those observed following administration of MenPS, at days 5, 7, and 28. CONCLUSIONS: This study showed sustained levels of bactericidal antibodies for at least 3 years after immunization of adolescents with MenCV. After challenge of immunized adolescents with MenPS, there was no increase in serum bactericidal assay observed until day 5 after vaccination, indicating that immunological memory may be too slow to generate protection against this potentially rapidly invasive organism.

Adolescent↗
PubMed2005

Meningococcal polysaccharide-protein conjugate vaccines.

It is now 5 years since the UK became the first country to introduce the serogroup C meningococcal polysaccharide-protein conjugate vaccines (MenC) into its routine immunisation schedule. This article reviews the global use of MenC with particular reference to the range of immunisation strategies used internationally. To date, concerns that MenC may result in an increase in meningococcal disease due to non-C serogroups have not been realised. The vaccine has proved to be highly safe and effective; however, concerns have arisen regarding the duration of vaccine effectiveness. Although booster doses of MenC may potentially extend the duration of protection offered by the vaccine, there are, as yet, no studies assessing this option. Clinical trials are underway to assess new combination conjugate vaccines (containing A, C, Y, and W polysaccharides), and it is probable that these more broadly protective vaccines will become available in the near future.

Adolescent↗
PubMed2005

Lack of serum bactericidal activity in preschool children two years after a single dose of serogroup C meningococcal polysaccharide-protein conjugate vaccine.

BACKGROUND: There is an increased risk of invasive meningococcal disease during the teenage years. A cohort of children vaccinated with a single dose of meningococcal C protein-polysaccharide conjugate (MenC) vaccine in early childhood during the U.K. catch up campaign will enter this age group during the coming decade. The duration of protective immunity against invasive meningococcal C disease provided by this single dose regimen is uncertain.A serum bactericidal titer of <1/8 correlates with susceptibility to invasive meningococcal disease. We assessed this correlate of protection in a cohort of children approximately 2 years after a single dose of vaccine. METHODS: Serum bactericidal activity was assessed in 94 children (median age, 4.0 years) at a median time of 1.8 years after vaccination. RESULTS: Of the 94 children, 59 (63%) had a serum bactericidal titer <1/8. CONCLUSION: The data from this study add to previous evidence indicating that immunity wanes rapidly after vaccination with serogroup C meningococcal glycoconjugate vaccines in infancy and early childhood. Such observations suggest that booster doses of MenC vaccine may be needed to maintain the successful contribution this vaccine has made to child health in the United Kingdom.

Antibodies, Bacterial↗