Informal workshop on potential regulatory and 2 licensing issues for pneumococcal conjugate vaccines. 13 June 1998,...

(1) It is likely that a seven-valent pneumococcal conjugate vaccine will be licensed in the next few years based on efficacy studies. Licensure of nine- or 11-valent vaccines will be sought soon thereafter. Further studies of nine- or 11-valent vaccines which can evaluate efficacy of the added serotypes will be unlikely. (2) Licensure of other vaccines (including those with additional serotypes), will depend on evaluation of surrogates for efficacy. (3) The most accepted surrogate of efficacy at this point is some combination of functional assay (e.g. opsonophagocytosis), and/or serology of anticapsular antibody by ELISA or RIA that correlates closely with the functional test. (4) An additional important correlate of immunity for polysaccharide conjugate vaccines may be measurement of the booster response. (5) Although effect on nasopharyngeal carriage may be developed into a useful correlate of efficacy in the future, much additional work must be done before carriage data can be interpreted usefully for this purpose. (6) Testing for consistency of production of pneumococcal conjugate vaccines will follow lines similar to that for Hib conjugate vaccines. Thus, instead of one set of universally applicable lot release criteria, vaccine-specific criteria must be developed collaboratively between industry and national control authorities.