Short and long-term effects of pandemic unadjuvanted influenza A(H1N1)pdm09 vaccine on clinical manifestations and autoantibody profile in primary Sjögren's syndrome

Despite WHO recommendations about the A/California/7/2009/H1N1-like virus vaccination, studies evaluating its possible influence on clinical manifestations and autoantibody profile in primary Sjögren's syndrome (SS) are scarce. The aim of this study was to evaluate the possible influence of the unadjuvanted A/California/7/2009/H1N1-like virus vaccination on clinical manifestations and autoantibody profile in SS in the short/long-term. Thirty-six SS patients (The American-European Consensus Group Criteria, 2002) and 36 healthy controls with comparable mean age and gender were evaluated before and 21-days after this vaccination regarding seroprotection/seroconversion, factor increase in geometric mean titer (FI-GMT) and side effects. New onset of disease flares and autoantibody profile [antinuclear antibodies, anti-dsDNA, anti-Ro(SSA)/La(SSB), anti-RNP/anti-Sm, rheumatoid factor, anti-alpha-fodrin, anticardiolipin and anti-beta2-glycoprotein-I] were assessed before, 21-days and 1-year after vaccination. Patients and controls had similar rates of seroconversion (77.8 vs. 69.4%, p = 0.42), seroprotection (83.3 vs. 72.2%, p = 0.26) and FI-GMT (p = 0.85). Disease duration, prednisone (2.1 ± 4.9 mg/day), methotrexate and azathioprine did not affect seroconversion (p > 0.05). Regarding short-term, no change in the frequency or levels of autoantibodies was observed (p > 0.05) and only mild side effects were reported in comparable rates to controls (p > 0.05). During 1-year follow-up, the frequency of new disease flares was similar to the previous year (11 vs. 19%, p = 0.51), and four patients developed positivity to one of the following specificities: anti-Ro(SSA)/anti-La/(SSB), anti-alpha-fodrin, or IgM anticardiolipin. None developed specific lupus autoantibodies. Of note, a significant increase in the mean levels of anti-Ro/SSA (p = 0.0001) and anti-La/SSB (p = 0.002) was detected after 1-year with no change in the other autoantibodies. This is the first study indicating that influenza A(H1N1)pdm09 vaccine induces long-term changes in autoantibody profile restricted to SS spectrum without a deleterious effect in disease course.