Assessing the stability-indicating properties of alternative potency assays for inactivated influenza vaccine.

Determination of the potency of a vaccine is critical to ensuring that an appropriate dose is delivered, lot-to-lot consistency is maintained, and that the formulation is stable over the life of the vaccine. The potency of inactivated influenza vaccines is determined routinely by the Single Radial Immunodiffusion (SRID) assay. A number of alternative potency assays have been proposed and have been under evaluation in recent years. The aim of this study was to compare a surface plasmon resonance-based assay and two different enzyme linked immunoassays against the current potency assay, SRID, and against mouse immunogenicity when haemagglutinin antigen of the A(H1N1)pdm09 component of an inactivated influenza vaccine is stressed by elevated temperature, low pH and freezing. This analysis demonstrated that the alternative assays had good correspondence with SRID for samples from most stress conditions and that the immunogenicity in mice corresponded with potency in SRID for all stress samples. Subject to further analysis, the assays have been shown to have the potential to possibly replace, and at least complement, SRID.

Lessons learned in shaping vaccine markets in low-income countries: a review of the vaccine market segment supported by the GAVI Alliance.

OBJECTIVES: The Global Alliance for Vaccines and Immunization (GAVI) anticipated that growing demand for new vaccines could sufficiently impact the vaccines market to allow low-income countries (LICs) to self-finance new vaccines. But the time required to lower vaccine prices was underestimated and the amount that prices would decline overestimated. To better understand how prices in the LIC vaccine market can be impacted, the vaccine market was retrospectively examined. DESIGN: GAVI archives and the published literature on the vaccine markets in LICs were reviewed for the purpose of identifying GAVI's early assumptions for the evolution of vaccine prices, and contrasting these retrospectively with actual outcomes. RESULTS: The prices in Phases I and II of GAVI-supported vaccines failed to decline to a desirable level within a projected 5-year timeframe. GAVI-eligible countries were unable to sustain newly introduced vaccines without prolonged donor support. Two key lessons can be applied to future vaccine market-shaping strategies: (1) accurate demand forecasting together with committed donor funding can increase supply to the LIC vaccines market, but even greater strides can be made to increase the certainty of purchase; and (2) the expected time to lower prices took much longer than 5 years; market competition is inherently linked to the development time for new vaccines--a minimum of 5-10 or more years. Other factors that can lower vaccine prices include: large-scale production or alternate financing mechanisms that can hasten vaccine price maturation. CONCLUSIONS: The impacts of competition on vaccine prices in the LIC new-vaccines market occurred after almost 10 years. The time for research and development, acquisition of technological know-how and to scale production must be accounted for to more accurately predict significant declines on vaccine prices. Alternate financing mechanisms and the use of purchase agreements should also be considered for lowering prices when planning new vaccine introductions.

Benefits and effectiveness of administering pneumococcal polysaccharide vaccine with seasonal influenza vaccine: an approach for policymakers.

For the influenza pandemic of 2009-2010, countries responded to the direct threat of influenza but may have missed opportunities and strategies to limit secondary pneumococcal infections. Delivering both vaccines together can potentially increase pneumococcal polysaccharide vaccine (PPV23) immunization rates and prevent additional hospitalizations and mortality in the elderly and other high-risk groups. We used PubMed to review the literature on the concomitant use of PPV23 with seasonal influenza vaccines. Eight of 9 clinical studies found that a concomitant program conferred clinical benefits. The 2 studies that compared the cost-effectiveness of different strategies found concomitant immunization to be more cost-effective than either vaccine given alone. Policymakers should consider a stepwise strategy to reduce the burden of secondary pneumococcal infections during seasonal and pandemic influenza outbreaks.