By Shereen Lehman
(Reuters Health) - In a small new study, skipping the flu vaccine was associated with a higher risk for trouble with a sense of smell or taste.
Researchers say the results are preliminary, but since respiratory viruses are a common cause of a lost ability to smell, it's possible that the flu could be a contributing factor.
Respiratory viruses can damage olfactory nerves directly and indirectly by causing inflammation. Sometimes the effect is temporary, but not always, Dr. Zara Patel and colleagues at the Emory University School of Medicine in Atlanta, Georgia write in JAMA Otolaryngology-Head and Neck Surgery.
"Patients who suffer from decreased or total loss of smell, called 'hyposmia' or 'anosmia' are deeply affected by this problem," Patel told Reuters Health by email.
"Compared to the other special senses, for example, loss of vision or hearing, the loss of smell is often thought of as relatively inconsequential, but this is far from the truth," Patel said.
People who can't smell may lose important safety mechanisms, such as the ability to smell smoke or spoiled food, Patel said. And 80 percent of taste is linked to smell, so a total loss of smell could ruin a person's ability to enjoy food and beverages and have a negative effect on their social life.
"This can (and often does) lead to deep depression and a drastic reduction in quality of life," Patel said, adding there is currently no established cure for the problem.
Patel said hundreds of different respiratory viruses might have an effect like this, including some 200 viruses that cause the common cold. But the influenza virus may be preventable with vaccines.
"I saw this as a potential opportunity to (look for) any association between rate of vaccination and rate of (olfactory) loss, and see if there's a way to eventually use this information," she said.
Patel and colleagues identified 36 patients with olfactory problems that started after upper respiratory infections. The average duration of loss of smell was about 19 months but ranged from three to 48 months.
They compared those patients to 38 patients of the same race, age and gender, but without olfactory problems.
Overall, only 19 percent of the group with smell problems had been vaccinated against the flu, compared to 42 percent of the group who had no loss of smell.
It's important to note this is a small study, and more research needs to be done, Patel cautioned.
Now her team needs to look at this same subject with more rigorously designed studies, she said.
Patel said viruses aren't the only cause of smell dysfunction - sinus disease, trauma and tumors are other potential causes.
She said a few people will spontaneously recover their sense of smell after losing it, but this chance decreases as time passes from the first month after the loss.
"If people realize they are not able to smell or taste as well as they used to, they should seek care from an otolaryngologist as soon as possible," Patel said. "Because the longer the amount of time that passes before they are able to start treatment, the less chance they have for recovery."
SOURCE: http://bit.ly/1GwePSx JAMA Otolaryngology-Head and Neck Surgery, online January 15, 2015.