Loss of Smell and Taste with COVID19

02D95E17-4823-4E14-897D-68D0A2227DCBLet’s get some terminology correct. COVID19 is the disease. SARS-CoV2 is the specific name given to the actual new virus that has been identified as the cause of COVID19. SARS-Cov2 is a new novel virus from the Coronavirus family. In lay terms, coronavirus is the general term we use to refer to this virus. However, it is worth knowing that Coronaviruses are a large family of viruses that cause respiratory infections. These can range from the common cold to more serious diseases. COVID19 is a completely new disease. We have never met this virus before. Whatever we know about this virus is only 6 months old. We are still learning and discovering.

The virus, like any other virus, is a submicroscopic infectious agent that replicates inside the living cells of an organism. Virus needs a host and gets transmitted from host to host. As far as we know today, the SARS-CoV2 gets transmitted via droplets (not airborne based on current available evidence – which may change), meaning, it is not like a powder that floats in the air, but it travels in suspension form through mucous droplets. A sneeze or a cough can transfer the virus via droplets spread. This virus can hang around on surfaces and be passed on from hand to hand contact. Like any respiratory virus, it enters the mucosal lining of the airway (nose, mouth, throat) and possibly eye mucous membrane. There are studies showing that the virus is alive in mucous secretions, saliva and tracheal airway secretions. Once the virus enters the host through the airway lining, it appears to mainly affect the respiratory airway organs (nose, sinuses, throat, lungs), but in severe forms, the virus seem to also affect the blood system, the heart and other organs. Some autopsy studies show microemboli or small blood clots, affecting the brain, liver and heart.

Loss of taste and loss of smell are officially recognised as symptoms of COVID19. From the Australian Department of Health Website: “People with coronavirus may experience symptoms such as fever, respiratory symptoms (coughing, sore throat, shortness of breath) and other symptoms can include runny nose, headache, muscle or joint pains, nausea, diarrhoea, vomiting, loss of sense of smell, altered sense of taste, loss of appetite and fatigue.” The challenge is that smell and taste are subjective senses that are extremely difficult to scientifically measure, and not everyone with COVID19 will suffer from this deficiency. How good are most people in identifying reduced taste (hypogeusia), change in taste (dysgeusia), loss of taste (ageusia), reduced smell (hyposmia), change in smell (dysosmia), phantom smell (phantosmia) or loss of smell (anosmia).

Smell (olfactory) and taste (gustatory) are overlapping chemical senses. They rely on particles (odorants) to dissolve in respiratory mucous and bind to taste and smell receptors before being turned into an electrical signal that goes through the trigeminal and facial nerves to the brain. Complex magical scientific stuff. Taste and smell are culturally/socially driven and has various degrees of refinements in different people. What smells good to one person may not smell good to another. The taste palate of a sommelier will be very refined compared to a college student who lives on Mac and Cheese as routine. On top of that, we know that smell dysfunction affects 20% of the general population and is most commonly caused by sinonasal disease, upper respiratory tract infections, head trauma, normal aging, and neurodegeneration. Up to 45% of all anosmia in the general population are due to post-infectious cause (following a common cold, viral or bacterial sinusitis, etc.)

In this context, we meet a new virus that seem to attack the respiratory lining. No surprise that anosmia and ageusia are common presentation. One published study has attempted to design an anosmia reporting tool (Kaye et al Otolaryngology Head & Neck Surgery 2020). They found that anosmia was noted in 73% of patients prior to COVID19 diagnosis and was the initial symptom in 26.6%. Some improvement was noted in 27% of patients (average 7 days). About 85% of patients in their cohort improved within 2 weeks. Several similar studies show that anosmia and ageusia is hard to measure, not 100% accurate and has an uncertain progression in the disease. Another study (Meng et al. American Journal of Otolaryngology 2020) puts the rate of anosmia in COVID19 positive patients to be between 33.9% to 68%. Not everyone with anosmia has COVID19 and not everyone with COVID19 has anosmia. Anosmia is the initial symptom in a minority of patients with COVID19. Children are affected too. The good news is that it does not affect everyone. If it does, the effect seem to only last about 2 weeks for the vast majority of cases. Are there any long-term data on permanent loss of taste or smell? We do not know. The pandemic is only 6 months long and we certainly do not have any long-term data so far on anything related to COVID19.

What if one suffers from long term olfactory and gustatory dysfunction? Social anxiety, nutritional disturbances, and depression are well acknowledged consequences of smell disorders. Moreover, it has been suggested that olfactory function and depression are interdependent (Cummings Otolaryngology Head & Neck Surgery 2019). This means that identifying and treating olfactory and gustatory disorders become critical in the long run.

The stakes are even higher if the sufferer is a chef, food critique or wine professional. Smell and taste are the essence of their art and living. What can we do to help restore the sense of smell and taste in these professionals?

Let me be clear, there is a lot of data on general treatment for loss of smell and taste but none that is directly related to COVID19 anosmia and ageusia. We extrapolate the science to be applied to this particular context. Currently no specific data on successes or failures of any of these recommendations as it relates to COVID 19. But here are some thoughts extrapolated from anosmia research in the past:

  1. Treat the COVID19. Get well from that. That’s the primary goal.
  2. Loss of smell means inability to smell smoke or fire. Ensure that fire alarms and safety devices are available to warn the sufferer of danger.
  3. Steroid oral medications and steroid nasal sprays have been shown to have some good effect for anosmia related to sinusitis. The results have not been universally perfect, but in general the treatment is safe and well tolerated. We do not have a strong scientific evidence to recommend a particular regime or dosing protocol. If smell and taste is critical, a trial of oral and nasal steroids could be considered if there are no contraindications. The nasal steroids need to be administered in Kaiteki position (Google it) to allow better delivery to the olfactory region high up on the roof of the nose.
  4. Olfactory training for severe prolonged loss, or in the context of a smell and taste professional. Olfactory training is a therapeutic approach that involves repeated and deliberate sniffing of a set of odorants on a daily basis over a number of months (usually 3 to 9 months). One of the first studies in relation to the effects of repeated exposure was performed in 2004 using androstenone, and since this time numerous other studies have demonstrated beneficial effects in postinfectious, posttraumatic, idiopathic, and Parkinson-related olfactory dysfunction, as well as in healthy participants. At present, olfactory training is usually performed using four odorants, one from each of the following odor “categories”: flowery, fruity, spicy, and resinous. The current 4 odourants are: phenylethylalcohol (rose), eucalyptol (eucalyptus), citronellal (lemon), and eugenol (cloves). Twice daily for a minmum of 12 weeks, up to 32 weeks. A recent meta-analysis of 13 studies found that the duration of olfactory training was significantly related to its effectiveness (Hummel et al Position Paper on Olfactory Dysfunction https://www.rhinologyjournal.com/Documents/Supplements/supplement_26.pdf ). Quote from their paper : “Given the low associated cost and high safety of olfactory training, it is an attractive treatment modality, which can be employed with relative impunity.” This means that as long as you are not delivering dangerous chemicals up the nose, olfactory training is safe and will probably be beneficial.

Hope this answers some questions you may have in your mind. Remember:

Stay home if you can.

Stay masked if you have to leave the house.

Stay away from others.

We’ll get through this together.


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