I am Amish Mustafa Khan, a researcher at Washington University who studies COVID-19 olfactory dysfunction, and recently published a study estimating that 0.7 and as many as 1.6 million Americans may have chronic olfactory dysfunction as a result o...

Is there anything we can do to try to get back our sense of smell? Or by chronic, do you mean it is permanently gone?

This really is the million dollar question. It is also the reason we wrote this paper, to highlight the need for more research that focuses on treatments for COVID-19 olfactory dysfunction. There is no strong evidence supporting the efficacy for most proposed interventions including intranasal corticosteroids. Smell training may benefit a subset of people. Our lab led by Dr. Jay F. Piccirillo is studying a number of interventions including modified smell training and intranasal theophylline.

Diagnostically, chronic olfactory dysfunction is that which lasts 6 months or greater. To my knowledge no one has studied continued rate of recovery beyond six months in COVID-19 olfactory dysfunction. However, it is reasonable to assume that there will be continued low-level rate of recovery beyond the 6 month time point.

My wife to this day, a year after contracting Covid (now vaxxed) still has trouble with detecting some smells. For those of us that aren’t as well versed in research terminology, does your study cover those who no longer have their olfactory senses intact or does it include those mildly affected as well?

The study estimates include those with anosmia (complete loss) and hyposmia (diminished smell).

The degree of smell loss is quantified in the clinical setting using the validated "Smell Identification Test" developed at University of Pennsylvania. It is literally a scratch-and-sniff test comprised of 40 multiple choice questions! A score of less than 34 out of 40 is considered abnormal. A score less than 19 implies complete loss of smell.

Is that test available to anyone outside the study?

Yes - It is the gold-standard test for making a confirmed diagnosis. Most otolaryngology physicians have them in their office.

Is there an at home test available so I don't have to pay a doctor bill?

Found one: https://sensonics.com/product/smell-identification-test/

Confirming that this is the official test.

Can you please explain in very simple terms how and why this virus affects taste and smell so much please.

I ask so I can explain a to someone who thinks that the taste/smell thing is proof that the virus is genetically engineered, given that there is no history of respiratory viruses causing the same issues with taste and smell.

Even prior to the COVID-19 pandemic, viral upper respiratory infections were the most common cause of chronic olfactory dysfunction, accounting for 20-40% of all cases. Viruses reported to be associated with olfactory dysfunction include adenovirus, rhinovirus (common cold), and influenza (flu).

What makes SARS-CoV-2 unique is the frequency and severity of the associated olfactory dysfunction. This may be due in part because SARS-CoV-2 has tropism (affinity) for receptors expressed in the olfactory region (ACE-2 and TMPRSS2).

Hi, Mr. Khan! Can I just start off by asking, what is chronic olfactory dysfunction? What are it's symptoms? What are the effects?

https://jamanetwork.com/journals/jamaotolaryngology/fullarticle/2786433

Olfactory dysfunction includes a wide breadth of pathology including:

1. Hyposmia: Diminished smell
2. Anosmia: Absent smell
3. Parosmia: Distortion of odors in the presence of an odor stimulus
4. Phantosmia: Detection of odors in the absence of an odor stimulus

To meet the criterion for "chronic", symptoms must persist for 6 months or greater.

Off topic, but I was a caretaker for a 100+ year old man - he was busy getting ready in the morning one day and came running out of the bathroom all excited - ''I CAN SMELL THAT, WHAT IS IT?!!! I was making bacon. He said it was the first thing he'd smelled in over 20 years.

From then on, he got bacon whenever he wanted it...

Thank you for sharing this endearing story!

Why was I still able to smell Whiskey then?

This is a great question!

You may still be able to "smell" whiskey. This is because injury to the olfactory nerve does not preclude the detection of irritants such as ethanol, acetic acid, and menthol which are detected by the trigeminal nerve. We use this to our advantage in the clinical and research settings by using menthol as a positive control!

Do you think scent training / smell training is effective in restoring COVID-19 related olfactory dysfunction?

Scent/smell training being regularly smelling known samples of (strong, known) scents, usually from essential oils, and trying to recall what the scents are. For example, sniffing a sample of lemon essential oil and remembering what "lemon" smells like.

Scent/smell training has been shown to be (possibly) useful for overcoming anosmia caused by non-COVID-19 conditions.

Great question!

There are several trials (original paper by Hummel et al) supporting the use of smell training to help recover olfaction after post-viral injury.

Olfactory nerves are exposed to the external environment, and therefore have regenerative capacity. They turnover every 30 days on average. Therefore, the theoretical basis for smell training is that exposure to odors may prime this regenerative capacity.

To my knowledge, there are no studies in the published medical literature specifically studying the efficacy of smell training in COVID-19 resultant olfactory dysfunction. However, our lab is currently working on publishing a randomized, clinical trial on this very topic!

It wasn't until my ex-husband was in his forties that it was discovered that he had Kallman's syndrome. He was originally told that he must have had a "bad cold" when he was a young child. What is your experience with that?

Kallman Syndrome is a genetic, not acquired disorder!

It is characterized by olfactory dysfunction and hypogonadism (i.e. low libido, erectile dysfunction, infertility).

Cool work!!!
Now did you discuss the p-values confidence intervals? 😂😂😂😂 Essential wusm clin epi stuff.

Haha! Who is this! Love this comment.

After you lose your sense of smell, can you get it back? How so?

Most people experience spontaneous recovery of smell within 2 weeks of convalescence from their infection.

With your extensive, professional knowledge on the subject, what would you say to convince a vaccine hesitant American to get themselves inoculated?

Edit: For my dad lol

I think someone with a background in dissemination and implementation science would be able to answer this question best. There has always been an implementation gap between evidence based medicine and routine clinical practice. Closing the gap requires a multi-disciplinary approach that engages various stake holders (i.e., primary care physicians, parents, patients, community leaders etc.). It is also important for us to recognize the historic context in which certain certain patient populations may be wary of allopathic medicine.

Would you agree that doing a daily smell test to see if you can smell is a good proxy test for covid infection, since it's free and easy?

Are you going to do a follow up study including the boosters? I'm interested to see if they prevent symptoms like this more than the second shot.

This question requires a complicated answer!

Diagnostic tests have two parameters:

1. Sensitivity: Highly sensitive tests have screening utility because they detect all individuals with potential disease, but also detect a significant number of false positives. A well-documented example is the anti-nuclear antibody (ANA). It is sensitive for Lupus. Almost all individuals with Lupus have a positive ANA, however so do a lot of other people (false positives).
2. Specificity: Highly specific tests are used for confirmation of disease. Specific tests often have a significant number of false negatives.

Certainly, olfaction is not specific for COVID-19 infection. Loss of olfaction can occur due to allergic rhinitis, other upper respiratory viruses, etc. It may be reasonably sensitive, and have utility as a screening test, however it remains to be seen if smell-based screening tests provide any advantage over a clinical screen for symptoms of COVID-19 (fever, cough, shortness of breath, fatigue, sore throat, rhinorrhea, diarrhea, etc.) and exposure history.

I read several pop science books about the neuroscience of smell a while back (before COVID), and several of them mentioned research that linked anosmia and subsequent onset of depression (and I believe there was some discussion of anosmia from aging and a possible link to dementia and other aging diseases).

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Do people see this with anosmia linked to COVID and is there any research happening on this? I feel like it would be useful for people with COVID anosmia to know about this phenomena if it's thought to be a real thing.

Great point! Olfactory dysfunction has been shown to decrease general quality of life, impair food intake and detection of harmful gas and smoke, enhance worries about personal hygiene, diminish social well-being, and initiate depressive symptoms. However, many individuals tolerate their olfactory loss, and do not suffer negative psychological consequences. There is a lot of heterogeneity in how people experience and interpret this chemosensory loss.

P.S. For edification, loss of smell is shown to be associated with Alzheimer and Parkinson Disease, but is not causative.

Great paper for reference: Ilona Croy, Steven Nordin, Thomas Hummel, Olfactory Disorders and Quality of Life—An Updated Review, Chemical Senses, Volume 39, Issue 3, March 2014, Pages 185–194

Is it physical damage or some sort of psychological damage or both?

Physical

Thanks. I probably worded that wrong perhaps more accurately is it the nose that’s damaged or the brain (neurological)

Good question!

There is data to support that both etiologies may play a role. Peripherally, through damage to sustentacular (support) olfactory cells located in the nasal cavity. Centrally, through neuro-invasion via the olfactory pathway. This simplified photo illustrates the location of the olfactory nerves in the nasal cavity in relation to the cranial fossa (brain).

https://en.wikipedia.org/wiki/Olfactory_bulb#/media/File:Head_olfactory_nerve_-_olfactory_bulb_en.png

You can appreciate the proximity of the olfactory nerves to the brain. In fact, there is an organism known as Naegleria fowleri (brain-eating amoeba) that follows this exact pathway through the nasal cavity to enter the brain!

0.7 on its own actually means nothing. You understand that, right? I mean you wrote it in both the title and the description. Doesn't actually inspire confidence.

The point estimate is 0.7 million (i.e., 700,000).