Effect of influenza vaccine on bronchoprovocation testing in normal subjects

A study of 55 nonasthmatic patients was undertaken to determine if recent influenza vaccination is a justifiable exclusionary criteria for bronchoprovocation testing. Healthy subjects without history of asthma and with negative methacholine challenge tests were given an intramuscular injection of killed influenza vaccine. Methacholine challenge testing was repeated 24 h later. While a statistically significant decline in FEV1 at 188 methacholine dose units was demonstrated (p < 0.018), this was not clinically significant; none of the 55 subjects converted a negative test to positive. We conclude that recent influenza vaccination is not a sufficient exclusionary criterion for methacholine challenge testing. Positive results in a patient recently vaccinated would still indicate asthma in the correct clinical setting.