Association of decreased rate of influenza vaccination with increased subjective olfactory dysfunction

Seasonal influenza causes significant morbidity and mortality, with cardiovascular and respiratory complications the most common among susceptible individuals. Upper respiratory tract infections (URIs) are known to precede olfactory dysfunction in some patients. To our knowledge, there has been no study assessing the possible relationship between influenza vaccination status and olfactory dysfunction.

To compare vaccination status of a group of patients with subjective olfactory dysfunction with that of a group of controls.

Retrospective medical record review and telephone survey in a matched case-control study. Forty-two patients were identified via diagnosis codes who presented to a tertiary care academic rhinologic center with subjective smell dysfunction over the course of 1 year. Only post-URI and idiopathic etiologies were included. Forty-two age-, sex-, and race/ethnicity-matched control patients were also selected.

Demographic data, influenza vaccination status, and smoking status were reviewed. χ² Testing was used.

We were able to obtain vaccination data for 36 of 42 patients in the olfactory dysfunction group and 38 of 42 in the control group. Seven of the 36 (19%) in the olfactory dysfunction group had received the vaccine in the year prior to presentation compared with 16 of 38 (42%) in the control group (P = .04).

Influenza vaccination seems to be associated with a decreased rate of subjective olfactory dysfunction. This is a preliminary finding, and further studies would be needed to elucidate the exact role of influenza and influenza vaccination in patients with olfactory loss.