Does influenza vaccination exacerbate asthma?: Analysis of a large cohort of children with asthma

Context: Although influenza vaccination is recommended for children with asthma, only a minority are vaccinated. One reason for low influenza vaccine coverage among children with asthma may be concern that influenza vaccination may induce an exacerbation of asthma. Objective: To evaluate the safety of influenza vaccination in children with asthma, we studied the incidence of hospitalizations and emergency department visits for asthma following influenza vaccination. Design: Retrospective cohort study-analysis of population-based computerized medical and vaccination records. Setting: Four large health maintenance organizations on the West Coast of the United States. Subjects: Children with asthma 1 through 6 years of age, identified by search of computerized databases of medical encounters and pharmacy prescriptions. Main Outcome Measures: Exacerbations of asthma. Results: In unadjusted analyses vaccination was associated with high rates of asthma exacerbations. However, after adjusting for asthma severity using a self-control method, the incidence rate ratios of asthma exacerbations after vaccination were 0.58 (95% confidence interval, 0.36-0.95), 0.74 (95% confidence interval, 0.47-1.17), and 0.98 (95% confidence interval, 0.76-1.27) during the 3 influenza seasons. Conclusions: After controlling for asthma severity, we found that influenza vaccination does not result in acute asthma exacerbations in children. Concern about possible exacerbation of asthma is not a valid reason to not vaccinate children with asthma against influenza.