Effect of prednisone on response to influenza virus vaccine in asthmatic children

Objective: To evaluate the immunogenicity of the influenza virus vaccine in children receiving short-course (a burst) prednisone therapy for acute ast hmatic exacerbations. Design: Prospective cohort study. Setting: Outpatient pediatric clinic of a military medical center. Patients: Children aged 6 months to 18 years requiring the 1996 influenza v irus vaccine were eligible for the study. A total of 58 children were enrol led initially. The control group included 37 asthmatic children requiring l ess than 900 mu g/d of inhaled prednisone and their siblings. The prednison e group included 21 children vaccinated at the beginning of a course of pre dnisone prescribed to treat an asthma exacerbation. Thirty-one control subj ects (84%) and 19 patients in the prednisone group (90%) completed the stud y. Dropout was due to failure to come in for the postvaccination serum samp ling. Interventions: All study patients underwent immunization with the 1996-1997 trivalent subvirion influenza virus vaccine (FluShield; Wyeth Laboratories Inc, Marietta, Pa) containing 15-mu g hemagglutinin antigens each of A/Tex as/36/91 (H1N1)(A/H1), A/Wuhan/359/95 (H3N2)(A/H3), and B/Beijing/184/93 (B ). The prednisone cohort received a burst of oral prednisone therapy (2 mg/ kg per day for 5 days). Main Outcome Measures: To assess the immunogenicity of the vaccine between both groups, at least a 4-fold rise in titer and end titers of at least 1:4 0 to each of the 3 antigens were compared. Mean changes in geometric titers to the 3 antigens were also compared. Results: Proportion of patients in each group with at least a 4-fold rise i n titer to each of the influenza antigens was as follows: for A/H3N3 antige n, 15 patients (79%) in the prednisone group vs 22 controls (71%) (P =.74); for A/H1N1 antigen, 16 patients in the prednisone group (84%) vs 20 contro ls (64%) (P =.20);and for B antigen, 7 patients in the prednisone group (37 %) vs 8 controls (26%) (P =.53). Proportion nf patients in each group with an end titer of at least 1.40 to each of the antigens was as follows: for A /H3N2 antigen, 18 patients in the prednisone group (95%) vs 28 controls (90 %) (P =.69); for A/H1N1 antigen, 17 patients in the prednisone group (89%) vs 26 controls (84%) (P =.99); and for B antigen, 7 patients in the prednis one group (37%) vs 13 controls (42%) (P =.99). There were also no significa nt differences between groups in the mean changes in geometric titers to an y of the 3 antigens. Conclusions: Prednisone bursts did not diminish the response of asthmatic c hildren to the 1996 influenza virus vaccine, compared with controls. Childr en can be effectively vaccinated against influenza virus while they are rec eiving prednisone therapy bursts for asthmatic exacerbations.