Immunogenicity of pneumococcal polysaccharide vaccine in adult systemic lupus erythematosus patients undergoing immunosuppressive treatment

Objective: To evaluate the immunogenicity of the 23-valent pneumococcal polysaccharide vaccine (PPSV23) in adult systemic lupus erythematosus patients undergoing (IS group) and not undergoing (non-IS group) immunosuppressive treatment.

Methods: In this prospective open-label study from February 2013 to April 2014, 54 patients had blood samples collected immediately before PPSV23 immunization and 4-6 weeks thereafter for the ELISA measurement of IgG antibody levels against seven pneumococcal serotypes. Positive vaccine response for each serotype was defined as a four-fold or greater antibody response over baseline levels or as a post-vaccine anti-pneumococcal IgG level ≥1.3 µg/ml when baseline values were <1.3 µg/ml. Patients should have responded appropriately to ≥70% of the tested serotypes. We also calculated the mean ratio of post- to pre-vaccination anti-pneumococcal IgG levels.

Results: Twenty-eight patients were classified into the IS group and 26 into non-IS group. The median dose of prednisone at baseline was ≤5 mg/day in both groups. Serotype-specific vaccine response rates were not significantly different between the groups. Less than 40% of patients responded adequately by both vaccine response criteria, being numerically lower among IS patients. The mean ratio of increase in anti-pneumococcal levels was 6.4 versus 4.7 (p = 0.001) in non-IS and IS groups, respectively.

Conclusion: The vaccine was poorly immunogenic, especially among adult systemic lupus erythematosus patients under immunosuppressive therapy.