IS H1N1 INFLUENZA VACCINE SAFE AND EFFECTIVE IN PATIENTS WITH SSc?

Abstract

Introduction. Immunosuppressed patients are potentially at risk to suffer from life-threatening pulmonary infections caused by H1N1. Although pulmonary disease is an important cause of morbidity in patients with SSc, low rates of influenza vaccination are still observed in this population due to lack of information and fear of adverse events. The recent WHO recommendation that the 2010–2011 trivalent seasonal flu vaccine must contain A/California/7/2009/H1N1-like virus reinforces the need to access the safety and efficacy of H1N1 vaccination in SSc patients. Patients and methods. One hundred twenty-seven patients and 234 controls were vaccinated with adjuvant-free influenza A/California/7/2009 (pH1N1) vaccine. All participants were evaluated pre- and 21 days post-vaccination and serology for anti-H1N1 was performed by haemagglutination inhibition (HI) assay (HIA). Efficacy was assessed by seroprotection and seroconversion rates and the factor increase in geometric mean antibody titre (GMT). Participants received a 21-day symptom diary card and were instructed to report local and systemic adverse events. Severe side effects were considered if hospitalization was required. Results. SSc patients had mean age of 52 (5.3) years, mean disease duration of 11.96 (7.9) years and a female predominance (93%). Of SSc patients, 69.3% had limited cutaneous disease, whereas 30.7% had diffuse cutaneous disease. Half of the patients were on immunosuppressant therapy (mostly AZA, MTX and CYC). Thirteen (10%) patients were taking CSs, but only two patients received a daily dose > 10 mg of prednisone. SSc patients and controls presented similar pre-vaccination GMT (11.2 vs 9.3; P = 0.094) and seroprotection rates (18.1 vs. 11.5%; P = 0.110). After vaccination seroprotection rates (81.1 vs 82.9%; P = 0.668) and GMT (134.4 vs. 122.9; P = 0.654) rose in both groups. Seroconversion rates (72.4 vs 76.9%; P = 0.372) and factor increase in GMT (12.0 vs 13.2; P = 0.553) were comparable in both groups. Disease-modifying antirheumatic drugs were not associated with reduced vaccination responses (P > 0.05). Immunization was well tolerated with mild local (7.1 vs 14.1%; P = 0.058) and minor systemic reactions (23.6 vs 25.6%; P = 0.704) in patients and controls, respectively. No severe side effect was reported.Conclusion. Vaccination against H1N1 was safe and induced a satisfactory response in patients with SSc, including in those under immunosuppressive therapy. Due to the inherent risks of lower respiratory infections in this group of patients, physicians should consider annually influenza vaccination recommendation.