Abstract
BACKGROUND: Pneumococcal vaccination is recommended to patients with rheumatoid arthritis (RA) and primary Sjögren's syndrome (pSS). However, little is known whether the diseases influence pneumococcal vaccine response. This study aimed to investigate antibody response and functionality of antibodies following immunization with 13-valent pneumococcal conjugate vaccine (PCV13) in RA patients or pSS patients without disease modifying anti-rheumatic drugs (DMARD), compared to patients with RA treated with DMARD or to healthy controls. METHODS: Sixty RA patients (50 without DMARD and 10 with MTX), 15 patients with pSS and 49 controls received one dose of PCV13. Serotype-specific antibody concentrations for pneumococcal polysaccharides 6B and 23F and functionality of antibodies (23F) were determined in serum taken before and 4-6 weeks after vaccination using ELISA and opsonophagocytic activity assay (OPA), respectively. Proportions of individuals with positive antibody response (i.e. ≥ 2-fold increase from prevaccination concentrations; antibody response ratio; ARR ≥ 2), percentage of individuals reaching putative protective antibody level (i.e. ≥1.3 μg/mL) for both serotypes, and difference in OPA were calculated. RESULTS: After vaccination, antibody concentrations for both serotypes increased in RA without DMARD (p < 0.001), pSS (p ≤ 0.05 and < 0.01) and controls (p < 0.001). Antibody responses to 6B and 23F were comparable in RA without DMARD (64% and 74%), pSS (67% and 53%) and controls (65% and 67%), but lower in the small group RA with MTX (both 20%, p < 0.01). Similarly, significant increases of patients reaching protective antibody levels were seen in RA without DMARD (p ≤ 0.001) and controls (p < 0.001). After vaccination, OPA increased significantly in controls, RA and pSS without DMARD (p < 0.001 to 0.03), but not in RA with MTX. CONCLUSIONS: Pneumococcal conjugate vaccine is immunogenic in RA and pSS patients without DMARD and in line with previous studies we support the recommendation that vaccination of RA patients should be performed before the initiation of MTX. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02240888. Retrospectively registered 4 September, 2014.