18 trials were included in a Cochrane review [Abstract] 1.
Protective effects of inactivated influenza vaccine during the influenza season: A single parallel-group trial, involving 696 children, assessed the protective effects of influenza vaccination. There was no significant reduction in the number, duration or severity of influenza-related asthma exacerbations. There was no difference in the forced expiratory volume in one second (FEV1) although children who had been vaccinated had better symptom scores during influenza-positive weeks.
Adverse effects of inactivated influenza vaccine in the first two weeks following vaccination:Two cross-over trials involving 1526 adults and 712 children (over three years old) with asthma compared inactivated trivalent split-virus influenza vaccine with a placebo injection. These trials excluded any clinically important increase in asthma exacerbations in the two weeks following influenza vaccination (risk difference 0.014; 95% Cl -0.010 to 0.037). There was no significant difference in measures of healthcare utilisation, days off school/symptom-free days, mean lung function or medication usage.
Effects of live attenuated (intranasal) influenza vaccination: There were no significant differences found in exacerbations or measures of lung function following live attenuated cold recombinant vaccine versus placebo in two small studies on 17 adults and 48 children. There were no significant differences in asthma exacerbations found for the comparison live attenuated vaccine (intranasal) versus trivalent inactivated vaccine (intramuscular) in one study on 2229 children (over six years of age).
Comment: The quality of evidence is downgraded by sparse data.
Clinical comment: The proportion of asthmatic patients who might contract influenza in a non-pandemic winter may be small, and similarly the proportion suffering an adverse event from the vaccine may also be low.
Primary/Secondary Keywords