Safety and Efficacy of Anti-Pandemic H1N1 Vaccination in Rheumatic Diseases

Plain-language summary

The prognosis of rheumatic diseases has improved considerably with development of therapy. However, infections are considered the most important cause of morbidity and mortality in this group of patients. One of the ways to prevent such complications is vaccination. In 2009, a new pandemic strain of influenza virus (A/H1N1/2009) has emerged raising major concerns for public health. Patients under immunosuppressive therapy have indication for immunization against influenza virus H1N1. There are, however, concerns about possibility of reactivation of autoimmune diseases, determine adverse events and insufficient immunogenicity in these patients. The lack of studies evaluating the efficacy and safety of the vaccine against influenza A(H1N1)/2009 in these rheumatic patients led to the development of this research. The objectives of this study are to evaluate the humoral response and safety of the vaccine virus A(H1N1)/2009 in immunosuppressed patients with rheumatic diseases compared to healthy controls. We have recruited 400 patients with rheumatoid arthritis, 350 with spondyloarthritis, 1000 with systemic lupus erythematosus (SLE), 150 with dermatomyositis (DM), 100 with mixed connective tissue disease, 150 with systemic vasculitis, 250 with systemic sclerosis (SSc) , 100 with Sjögren's syndrome, 100 with antiphospholipid syndrome, 100 patients with juvenile idiopathic arthritis, 80 with juvenile SLE, and 80 with juvenile DM, followed at our Rheumatology Outpatient Division and Unit Pediatric Rheumatology Children's Institute, HC-FMUSP. The control group was recruited were 200 healthy employees of ICHC-FMUSP. Informed consent was obtained from all participants and the study was approved by the Local Ethical Committee. All subjects were vaccinated against influenza virus A/(H1N1)/2009 (vaccine approved and supplied by Instituto Butantan-São Paulo). Blood samples was collected to measure levels of antibodies inhibiting hemagglutination by influenza virus A (H1N1)/2009 immediately prior to vaccination and 21 to 28 days after vaccination., Participants fulfilled a questionnaire on the immediate side effects of the vaccine. All patients with rheumatoid arthritis, spondyloarthritis, SLE, DM, systemic vasculitis, juvenile idiopathic arthritis, juvenile SLE, and DM were assessed before and 21 days after vaccination for clinical, laboratory parameters of disease activity as well as treatment. Continuous variables will be compared by t-test to evaluate differences between patients with rheumatic diseases versus healthy controls. Differences between categorical variables will be evaluated using the chi-square or Fisher exact test. Statistical significance was set at p\<0.05.

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