The novel recognition of a diverse vaccine immunogenicity profile in distinct ARDs supports the notion that a booster dose may be recommended for diseases with suboptimal immune responses. This large study also settles the issue of vaccine safety. (ClinicalTrials.gov #NCT01151644).

Objective. Recent findings demonstrated a reduced immunogenicity of the influenza A H1N1/2009 vaccine in juvenile rheumatic diseases. However, a point of concern is whether the vaccine could induce disease flares. The aim of this study was to assess the disease safety of and the possible influence of disease parameters and therapy on nonadjuvant influenza A H1N1 vaccine response of juvenile systemic lupus erythematosus (SLE) patients. Methods. One hundred eighteen juvenile SLE patients and 102 healthy controls of a comparable age were vaccinated. Seroprotection rate, seroconversion rate, and factor increase in geometric mean titer (GMT) were calculated and effective immune response was defined by the Food and Drug Administration and the European Committee for Proprietary Medicinal Products vaccine immunologic standards. Disease parameters, treatment, and adverse events were evaluated. Results. Age was comparable in juvenile SLE patients and controls (mean ؎ SD 16.0 ؎ 3.5 versus 15.9 ؎ 4.5 years; P ‫؍‬ 0.26). Three weeks after immunization, seroprotection rate (73.7% versus 95.1%; P < 0.001), seroconversion rate (63.6% versus 91.2%; P < 0.001), GMT (90.8 versus 273.3; P < 0.001), and factor increase in GMT (8.1 versus 19.9; P < 0.001) were significantly lower in juvenile SLE patients versus controls. Nonseroconversion was associated with a higher frequency of patients with a Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score >8 (48.8% versus 24%; P ‫؍‬ 0.008) and a higher mean ؎ SD current glucocorticoid dosage (18 ؎ 21.4 versus 10.5 ؎ 12.5 mg/day; P ‫؍‬ 0.018). Multivariate logistic regression including a SLEDAI-2K score >8 revealed that only the SLEDAI-2K remained a significant factor for nonseroconversion (odds ratio 0.42, 95% confidence interval 0.18 -0.98; P ‫؍‬ 0.045). Disease parameters remained stable throughout the study and no severe vaccine adverse events were observed. Conclusion. The present study demonstrated adequate disease safety and is the first to discriminate that high disease activity impairs influenza A H1N1/2009 vaccine antibody production in juvenile SLE, in spite of an overall immune response within recommended levels.

Pandemic influenza A H1N1/2009 vaccine response is diminished in SLE under immunosuppressive therapy and antimalarials seems to restore this immunogenicity. Trial registration. www.clinicaltrials.gov, NCT01151644.

Background Reduced response to pandemic (2009) H1N1 (pH1N1) vaccine in patients with rheumatoid arthritis (RA) was recently reported. Objectives To evaluate the contribution of age, disease activity, medication and previous antibody levels to this reduced response. Methods 340 adult RA patients and 234 healthy controls were assessed before and 21 days after adjuvant-free influenza A/California/7/2009 (pH1N1) vaccine. Disease activity (DAS28), current treatment and pH1N1 antibody titres were collected. Seroprotection, seroconversion and factor increase in geometric mean titre (GMT) were calculated and adverse events registered. Results RA and controls showed similar (p>0.05) prevaccination GMT (8.0 vs 9.3) and seroprotection (10.8% vs 11.5%). After vaccination a significant reduction (p<0.001) was observed in all endpoints: GMT and factor increase in GMT, seroprotection and seroconversion rates. Disease activity did not preclude seroconversion or seroprotection and remained unchanged in 97.4% of patients. Methotrexate was the only disease-modifying antirheumatic drug associated with reduced responses (p=0.001). Vaccination was well tolerated. Conclusions The data confirmed both short-term anti-pH1N1 vaccine safety and, different from most studies with seasonal influenza, reduced seroprotection in RA patients, unrelated to disease activity and to most medications (except methotrexate). Extrapolation of immune responses from one vaccine to another may therefore not be possible and specific immunisation strategies (possibly booster) may be needed. Clinicaltrials.gov no NCT01151644.

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