Effects of inactivated influenza vaccine on respiratory illnesses and asthma-related events in children with mild persistent asthma in Asia.

BACKGROUND Acute asthmatic exacerbation and readmission may be associated with severe influenza infection and asthmatic children are a priority group for influenza vaccination. To date, our study is the first to evaluate the outcome of the influenza vaccine in asthmatic Asian children. OBJECTIVE To analyze the outcomes of inactivated influenza vaccine in children with mild persistent asthma METHODS A cross sectional non-randomized study was performed on 93 mild persistent asthmatic children who attended the Pediatric Allergy clinic between June 2012 in Chiang Rai Hospital and August 2013. Forty eight patients were immunized with 2 doses of inactivated influenza vaccine at one month interval. Respiratory illnesses and asthma-related events were compared between the immunized and the un-immunized groups. RESULTS The two study groups had similar demographic and clinical characteristic except with regards to eczema, including asthma controllers and skin prick testing results. One year after the vaccine was administered, the immunized group had significantly reduced acute respiratory tract illnesses, asthma exacerbations, ER visits, bronchodilator usage and systemic steroid administrations. Hospitalizations (p < 0.001) and their duration (p < 0.034) were also reduced in the immunized group. CONCLUSIONS Immunization of inactivated influenza vaccine in children with mild persistent asthma decreased respiratory illnesses and asthma-related events.