Association of Influenza Vaccinations and Asthma Exacerbations among Asthmatic Children in the US

Experts recommend that all asthmatic children older than six months receive an annual influenza vaccination; however, it is unknown if the influenza vaccine is effective in preventing asthma exacerbation. We sought to determine the impact of receiving an influenza vaccination on having an asthma attack and visiting the emergency room for asthma during a 12 month period among a nationally representative, population-based sample of asthmatic children. We examined data on 8,423 children who had ever received a diagnosis of asthma from the 2005-2010 National Health Interview Survey. Receipt of flu shot or spray, occurrence of an asthma episode/attack, and visiting the ER due to asthma were examined during a 12 month window. All analyses adjusted for propensity to receive the flu vaccine, asthma severity, and sociodemographic characteristics. Despite recommendations, influenza shot levels among asthmatic children are generally low, with only 37.7% receiving a flu shot or spray in the 12 months prior to the survey. Asthmatic children who received the flu shot were 1.34 times as likely (95% CI: 1.22-1.48) to experience an asthma attack and 1.18 times as likely (95% CI: 1.01-1.38) to visit the ER for asthma as those who did not receive a flu shot; children who received the flu spray were not at an increased risk for an asthma attack or an ER visit. The intramuscular flu vaccine may not be effective in preventing asthma exacerbation in children, and may in fact lead to increased asthma exacerbations. Additional investigation, not limited by cross-sectional data, is warranted.