Objective: Influenza immunization is recommended for children with chronic conditions and children receiving chronic acetylsalicylic acid therapy. Our study assessed the safety and immunogenicity of this vaccination in children with chronic arthritis.
Methods: The frequency of possible adverse reactions following influenza vaccination, and virus specific HI antibody levels prior to and 4 weeks after vaccination with an inactivated split virus vaccine prepared for the 1991/92 season, were assessed in a prospective open study of children with chronic arthritis. Thirty-four patients were assessed clinically at vaccination and one month later. Local symptoms at the injection site and systemic symptoms were assessed by diary in 26 patients and 13 immunized healthy control children.
Results: Tenderness and/or redness at the injection site, and fever occurred equally in patients and controls. Malaise/nausea occurred in 12 patients and 3 controls (p = 0.3), but patients had more symptomatic days than controls (p = 0.01). No child with inactive arthritis developed a swollen joint following immunization. There were no significant differences between the 2 visits for a.m. stiffness, pain (VAS), global assessment, joint count or erythrocyte sedimentation rate (ESR). More patients improved than deteriorated by each measure. Three patients deteriorated by global assessment, 7 patients had an increased joint count. At least 95% of patients developed presumably protective levels of antibodies (HI titers > or = 40) to each virus. Preimmunization titers, seroresponse rates (4 x rise or rise from < 20 to > or = 40) and final titers were the same between patients (whether or not they were taking prednisone or a second line antirheumatic drug) and controls.
Conclusion: There was no convincing evidence that influenza vaccination is associated with significant adverse reactions or arthritis flares in children with chronic arthritis. Children with chronic arthritis appeared to respond adequately to influenza vaccination.