For a reliable assessment of the immunogenicity of pneumococcal vaccination among patients with systemic lupus erythematosus (SLE), a minimum number of individual serotypes need to be tested when evaluating antipneumococcal antibody responses to offset variations in serotype-specific immunogenicity, according to results of a post hoc exploratory analysis published in the Annals of the Rheumatic Diseases.1

In addition, pneumococcal serotypes with a high prevaccination-specific antibody should be disregarded from the evaluation when interpreting vaccine response using quantitative increase in antipneumococcal antibody titers (anti-PnAbs).

The investigators performed a post hoc analysis on antipneumococcal antibody responses of 54 adult patients with SLE who had previously been immunized with the 23-valent pneumococcal polysaccharide vaccine.2 Overall, 78% of these patients already had high prevaccination anti-PnAbs of ≥1.3 µg/mL against ≥1 of the 7 pneumococcal serotypes that were tested.

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Results of the study showed that high preimmunization anti-PnAbs increased significantly less after vaccination compared with low preimmunization anti-PnAbs (1.87-fold increase in geometric mean concentration vs 2.30-fold increase in geometric mean concentration, respectively; P <.0001). Of note, when the basal antipneumococcal value was ≥1.3 µg/mL, none of the titers increased 4-fold after vaccination.

For serotypes with a preimmunization anti-PnAb <1.3 µg/mL, achieving a ≥3-fold response in titers was associated with a seroconversion rate of 100%, as opposed to seroconversion rates of 11% and 82% for a <2-fold response and a 2.0-fold to 2.9-fold response, respectively (P <.0001 for both rates vs 3-fold responses). According to a binary logistic regression analysis that examined whether any of the 7 serotypes were more likely to result in seroconversion, serotype 14 proved to be the most capable (odds ratio, 3.43; 95% CI, 1.08-10.93; P =.037).

The investigators concluded that high prevaccination anti-PnAbs prevented a 4-fold response to immunization in this population of patients with SLE. Moreover, pneumococcal vaccine seroconversion was best associated with a ≥3-fold increase in anti-PnAbs. Therefore, if pneumococcal serotypes with high preimmunization-specific antibody levels are not included when conducting an analysis, this will allow immunogenicity studies of pneumococcal vaccination to be more comparable.

References

1. Rezende RP, Andrade LEC, Klumb EM. 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 [published online February 1, 2019]. Ann Rheum Dis. doi: 10.1136/annrheumdis-2018-214888

2. Rezende RP, Ribeiro FM, Albuquerque EM, Gayer CR, Andrade LE, Klumb EM. Immunogenicity of pneumococcal polysaccharide vaccine in adult systemic lupus erythematosus patients undergoing immunosuppressive treatment. Lupus. 2016;25(11):1254-1259.