Influenza and asthma

The relationship between infections of the respiratory tract and exacerbati ons of pulmonary symptoms in individuals with asthma is well established on clinical grounds. Patients having an acute attack of asthma often give a h istory of a "cold" before the onset of the exacerbation. The identification rare of pulses during exacerbations of asthma (10-30%) is much higher than the viral identification rate generally found during asymptomatic periods in asthmatics (3%). The mechanisms whereby upper respiratory viruses might induce or contribute to attacks of asthma are currently unknown: epithelial damage, increased c ytokines releasability, mouth breathing... influenza vaccination is recomma nded in patients with chronic pulmonary diseases. Hoevever, bronchial hyper reactivity has been reported after influenza vaccination in asthmatics. Rea ctions to these vaccines may be due to non-immunogenic impurities, which ar e not present in the more recently developed subunit vaccines. In spite of the lack of double-blind studies between subunit and killed influenza virus vaccines, and because of the potential bad prognosis of influenza infectio n on airway obs obstruction, influenza vaccination should be recommended in asthmatics with stable respiratory function but influenza vaccination rate remains low.