An experimental bivalent meningococcal outer membrane vesicle (OMV) vaccine (B:4:P1.19,15 and B:4:P1.7-2,4) has been developed to provide wide vaccine coverage particularly of the circulating strains in Europe. A randomized, controlled phase II study (study identification number, 710158/002; ClinicalTrials.gov identifier number, NCT00137917) to evaluate the immunogenicity and safety of three doses of the OMV vaccine when given to healthy 12-to 18-year-olds on a 0-2-4 month (n ؍ 162) or 0-1-6 month schedule (n ؍ 159). A control group received two doses of hepatitis A and one of conjugated meningococcal serogroup C vaccine on a 0-1-6 month schedule (n ؍ 157). Immune response, defined as a fourfold increase in serum bactericidal titer using a range of vaccine-homologous or PorA-related and heterologous strains, was determined for samples taken before and 1 month after vaccination; assays were performed at two laboratories. As measured at the GlaxoSmithKline (GSK) laboratory, the OMV vaccine induced an immune response against homologous or PorA-related strains (in at least 51% of subjects against strains of serosubtype P1.19,15 and at least 66% against strains of serosubtype P1.7-2,4) and against a set of three heterologous strains (in 28% to 46% of subjects). Both laboratories showed consistent results for immune response rates. The OMV vaccine had a similar reactogenicity profile for each schedule. Pain preventing normal activities occurred in approximately one-fifth of the subjects; this was significantly higher than in the control group. The immune responses induced by the bivalent OMV vaccine demonstrated the induction of bactericidal antibodies against the vaccinehomologous/PorA-related strains but also against heterologous strains, indicating the presence of protective antigens in OMVs and confirming the potential of clinical cross-protection.
An open-label randomized study was undertaken to compare a 2-dose regimen (Months 0 and 6) of hepatitis B surface antigen (HBsAg) vaccine formulated with a novel adjuvant (HBsAg/AS04) with a standard 3-dose regimen (Months 0, 1 and 6) of licensed recombinant HBsAg vaccine in terms of immunogenicity and reactogenicity when administered to healthy subjects aged between 15 and 40 y. At 1 and 6 months after the full vaccination course there was a 100% seroprotection rate (anti-HBs > or = 10 mIU/ml) with the HBsAg/AS04 vaccine, compared with a 99% response rate with the licensed vaccine. The corresponding geometric mean titres were significantly higher for the novel vaccine compared to the standard vaccine: 15,468 and 2,745 mIU/ml at Months 7 and 12 vs. 6,274 and 1,883 mIU/ml, respectively. There was a higher prevalence of local symptoms with the adjuvant vaccine (90% of doses) than with the standard vaccine (48% of doses). However, these symptoms (pain, swelling and redness) were predominantly of mild-to-moderate intensity and resolved rapidly without treatment. A 2-dose regimen of the new HBsAg/AS04 adjuvant vaccine therefore compared favourably to the standard regimen in healthy young adults. It is anticipated that the simplified vaccination schedule may improve compliance and reduce costs.
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