A/H1N1 influenza vaccination in patients with systemic lupus erythematosus: Safety and immunity

Objectives: To determine the safety of and immunogenicity induced by A/H1N1 influenza vaccination in patients with systemic lupus erythematosus (SLE). Research design and methods: The study population comprised 21 SLE patients and 15 healthy control subjects who underwent split-virion, inactivated monovalent A/H1N1 vaccination between December 2009 and January 2010. Sera were obtained before, three weeks after, and six months after vaccination. SLE disease activity index (SLEDAI) scores and autoantibodies were measured at every visit in SLE patients. Haemagglutination inhibition and the serum immunoglobulin G (IgG) level were calculated using the World Health Organization (WHO) procedure to evaluate the antibody responses. We also recorded current medications and past seasonal influenza vaccinations to analyse the interactions between vaccinations and the autoimmunity of SLE patients. Results: The mean age of the enrolled population was 34.3 years for SLE patients and 39.4 years for control subjects. The average SLEDAI score for SLE patients was 4.1 at vaccination, 4.5 at three weeks, and 4.3 at six months. The seroprotection rate at three weeks was 76.2% in SLE patients and 80.0% in healthy control subjects; by six months, the seroprotection rate was 66.7% in SLE patients and 60% in healthy control subjects. The seroconversion rate was 76.2% in SLE patients and 80% in healthy controls at three weeks; by six months, the seroconversion rate was 52.4% in SLE patients and 53.3% in healthy controls. The response in SLE patients met the criteria of the European Committee for Proprietary Medicinal Products guidelines at three weeks, while the percentage of seroprotection did not at six months. The clinical disease activity and SLEDAI scores did not differ significantly from before to after vaccination in SLE patients, although the level of anticardiolipin IgG increased at three weeks after vaccination, but with no apparent clinical manifestations. Conclusions: The A/H1N1 influenza vaccine is safe and effective in SLE patients and has no obvious adverse clinical effects. Treatment with a single immunosuppressive agent or combination therapy also leads to effective humoral immunity in these patients.