Revisiting the issue of how to assess pneumococcal vaccine immunogenicity: a post hoc analysis of antipneumococcal antibody responses among adult patients with systemic lupus erythematosus previously immunised with 23-valent pneumococcal polysaccharide vaccine

A judicious analysis and comparison of studies on the immunogenicity of pneumococcal vaccine in patients with systemic lupus erythematosus (SLE)1–9 is hampered by wide heterogeneity in several factors, including differences in the immunoassays performed, cut-off levels used as serological correlates of protection, number of individual serotypes as well as types of capsular antigens analysed, response criteria, and SLE-related immunosuppressive treatment. In addition, how to interpret vaccine response when preimmunisation antipneumococcal antibody titres (anti-PnAbs) are already high (or protective) is not yet clear, which is of relevance given that non-immunised adults often have high antibody levels for some serotypes as a result of prior pneumococcal infections. Moreover, only a minority of individuals with high prevaccination anti-PnAbs are reportedly capable of mounting a ≥4-fold rise in …