A phase III clinical trial has recently been completed [22]. In summary, prior to June 2012, there was no vaccine licensed in the US for CP-690550 molecular weight the prevention of meningococcal disease in infants. The

combination of Nm serogroups C and Y polysaccharides together was specifically chosen for development to meet a need in the US for prevention of MenC and MenY IMD in infants and was manufactured together with Hib to obviate an additional injection at each infant vaccination [23]. The Vaccine HibMenCY-TT is a combination of three discrete polysaccharide–protein conjugates. Each 0.5 mL dose of HibMenCY-TT contains 2.5 μg of Hib capsular polysaccharide (polyribosylribitol phosphate [PRP]) and 5 μg each of MenC and MenY polysaccharide individually conjugated or bound to tetanus toxoid. The total amount of tetanus toxoid is approximately 17.75 μg. HibMenCY-TT does not contain adjuvant or preservative. HibMenCY-TT is supplied as a single-dose vial of lyophilized vaccine to be reconstituted with the accompanying vial of saline diluent [24]. Mechanism of Action Due to the low incidence of meningococcal disease, as for other novel meningococcal vaccines, efficacy trials of HibMenCY-TT were impractical and effectiveness was inferred based on demonstration of immunogenicity and achievement of presumed correlates of protection [25]. Serum bactericidal

activity (SBA) is a functional assay that measures killing of Nm by antibodies contained in the patient’s serum in the presence of complement. The https://www.selleckchem.com/products/CP-673451.html complement source may be human (hSBA) or rabbit PF 2341066 (rSBA). For hSBA, a titer of ≥4 is the accepted correlate of protection

for serogroup C based on clinical effectiveness [26]. For rSBA, a more conservative titer of ≥8 has been found to be most consistent with clinical efficacy of conjugate vaccines against serogroup C disease [25, 27]. Of note, this low bactericidal titer (with rabbit complement) does not necessarily indicate that bactericidal activity is the mechanism of immune protection (e.g., it may be a marker for an alternative mechanism such as human complement-enhanced opsonic antibody [28]). For serogroup Y, no true correlate of protection exists and the same hSBA and rSBA titers as for MenC have been accepted as surrogates of protection [27]. Due to the virtual Amisulpride elimination of Hib disease through routine vaccination, efficacy trials of novel Hib vaccines are not feasible. Effectiveness of the Hib polysaccharide in HibMenCY-TT was inferred based on comparative trials with other licensed Hib vaccines with non-inferiority of immunogenicity as the end-point. Based on an efficacy trial with Hib polysaccharide vaccine in Finland, it has been widely accepted that an anti-PRP antibody concentration of ≥0.15 μg/ml is adequate to confer short-term protection, and an anti-PRP concentration of ≥1.0 μg/ml is required for long-term protection (or protection for the following 12 months) [29, 30].