Influenza vaccination of children during acute asthma exacerbation and concurrent prednisone therapy.

OBJECTIVES: The influenza vaccination rate is very low among children with moderate to severe asthma. This may be partly because of poor patient motivation and failure to visit clinics for vaccination. Another important factor may be health care providers' deferral of vaccination because of concern about the efficacy and safety of influenza vaccination during asthma exacerbations and concurrent prednisone therapy. We therefore examined the safety and immunogenicity of influenza vaccination during acute asthma exacerbation with concomitant prednisone therapy.

SETTING: A pediatric allergy and pulmonology clinic and a pediatric emergency department.

DESIGN: Children (n = 109) with a known diagnosis of asthma 6 months to 18 years of age were recruited. All participating patients, 59 without asthma symptoms (no prednisone, control group) and 50 with acute asthma exacerbation requiring prednisone burst therapy (prednisone group) received trivalent subvirion influenza vaccine. Fifteen children in the control group and 12 in the prednisone group received a booster dose according to American Academy of Pediatrics guidelines. Serum antibody titers to influenza A/Beijing/32/92 (H3N2), influenza A/Texas/36/91 (H1N1), and influenza B/Panama/45/90 were measured before and 2 weeks after vaccination. Adverse effects noted within 48 hours after vaccine dose were ascertained during the follow-up visit.

RESULTS: The antibody response was analyzed by comparing mean postvaccine titers, the percentage of patients achieving protective antibody levels (> or = 5log2), and the percentage of patients achieving rises in titers of 2log2 or greater. Antibody responses to influenza A/Beijing/32/92 (H3N2) and influenza A/Texas/36/91 (H1N1) in the prednisone-treated and control groups were not different. A significantly better response to the influenza B/Panama/45/90 antigen was seen in the prednisone group for all three parameters. Children who received a booster dose and the subgroup of children with low prevaccination titers (< or = 3log2) showed similar patterns. Adverse effects, including asthma exacerbation, local swelling at the injection site, fever, rash, and headache, were not different in the two groups.

CONCLUSIONS: Influenza vaccination can be given safely and effectively to asthmatic children regardless of asthma symptoms or concurrent prednisone therapy when necessary. Vaccination of all moderate to severe asthmatic patients visiting clinics or emergency departments would improve the overall vaccination rate significantly.