While fever, cough and shortness of breath characterise the disease caused by the novel coronavirus, the Centers for Disease Control and Prevention (CDC) updated its list of common symptoms in late April 2020 to include a new loss of smell or taste, according to Vanderbilt University’s Medical Center. 

A recent review by Healthine evaluated eight studies with a total of 11,054 Covid-19 patients. According to the review, loss of smell and taste often happens prior to other Covid-19 symptoms.

A study earlier in the pandemic found that loss of smell was more closely associated with outpatient care as opposed to hospital admission. 

According to Dr Fabrice Iradukunda, a Covid-19 front liner in Kigali, the most common symptoms of Covid-19 are shortness of breath, dry cough, headache and fatigue.

He says that there are no studies in literature regarding the possible relationship between coronavirus and the development of taste and smell disorder, but this is some of the relation.

"Angiotensin-converting enzyme 2–ACE2 (an  enzyme attached to the cell membranes of cells located in the lungs, arteries, heart, kidney, and intestines) is expressed on the nasal mucosa, where it participates in respiratory inflammatory diseases by regulating the levels of inflammatory peptides, such as bradykinin,” he says.

Iradukunda says that in Covid-19 patients, such an important inflammatory component doesn’t seem to be present and the alteration of the sense of smell is generally not accompanied by rhinitis symptoms.

Therefore, the hypothesis could be that the alterations are due to damage caused by the virus to the olfactory pathways. Olfaction is the sense of smell, he adds.

According to Medical News Today, a loss of taste and smell is a common early symptom of Covid-19. Therefore, anyone who notices changes in these senses should start self-isolating and get a Covid-19 test. Changes might include, taste and smell being less sensitive than normal, no sense of smell or taste, foods tasting strange and odours smelling unusual.

Iradukunda explains that there are no studies regarding the possible relationship between coronavirus and the development of taste and smell disorder, but in most cases, smell and taste alteration resolves, it is not permanent. 

It may resolve within four weeks. If it persists, you have to consult a doctor.

He recommends seeking medical care if you have any symptoms of Covid-19, such as shortness of breath, dry cough, fever, headache and fatigue.

Iradukunda says that anything that irritates and inflames the inner lining of the nose and makes it feel stuffy, runny, itchy, or drippy can affect your senses of smell and taste. This includes the common cold, sinus infections, allergies, sneezing, congestion, the flu, and Covid-19.

How severe is the loss of taste and smell with Covid-19?

According to one 2020 study, a sudden, severe loss of taste and smell in the absence of an allergy or other chronic nasal condition could be an early symptom of Covid-19. 

However, Medical News Today notes that if someone is experiencing any sort of unexpected dysfunction in taste and smell, even if it is mild, they should self-isolate and test for Covid-19. This loss of taste and smell may occur in people who have no other symptoms of Covid-19.

Doctors suggest that most of the time, mild cases of Covid-19 can be treated at home. However, in some cases the illness can become more serious. This is more likely in older adults and in individuals with certain underlying health conditions, such as; diabetes, obesity, chronic obstructive pulmonary disease (COPD), heart disease, making it necessary to seek emergency medical care immediately if you experience difficulty breathing, chest pain or pressure that doesn’t go away, lips, face, or fingernails that are blue in colour, confusion and trouble staying awake or difficulty waking up. 

What else can cause you to lose your sense of taste or smell?

"In addition to Covid-19, there are many other factors that can cause you to lose your sense of smell or taste. These include; smoking, other upper respiratory infections, such as colds, the flu, or sinus infections, allergies, nasal polyps, a head injury, neurological conditions, including Parkinson’s disease, multiple sclerosis, and Alzheimer’s disease, medications—such as some types for blood pressure, antibiotics, or antihistamines—and hormonal changes due to conditions like hypothyroidism or Cushing’s syndrome,” states Healthline.