Loss of smell and taste can predict COVID-19 early

Loss of smell and taste found out to be early symptoms of COVID; early diagnosis can cut viral transmission

Increased awareness of this fact may encourage earlier diagnosis and treatment, as well as heighten vigilance for viral transmission. Photo: iStock

Just before starting his shift in the third week of May this year, Dr A Ravi, nodal officer, Government Stanley Medical College Hospital, had ordered breakfast from a hotel nearby.

Finding it totally bland, he contacted the restaurant to complain and he was informed that they have not received any such complaint regarding the South Indian breakfast from another customer. He promptly decided to get himself tested and the same day he was diagnosed with COVID-19.

While Dr Ravi is among many other patients across the country, who have reported the symptoms of loss of smell and taste, the set of symptoms was added to nine others by the Ministry of Health and Family Welfare in the revised clinical management protocols released last week. The others included fever, cough, fatigue, shortness of breath, expectoration (ejecting phlegm or mucus), myalgia (muscle ache or pain), rhinorrhoea (runny nose), sore throat and diarrhoea.


According to the data from Integrated Health Information Platform and Integrated Disease Surveillance Programme, portal case investigation forms for COVID-19, the details on the signs and symptoms reported are (as on June 11), fever (27 per cent), cough (21 pc), sore throat (10 pc), breathlessness (8 pc), weakness (7 pc), running nose (3 pc) and others (24 pc). The loss of smell and taste have been accounted for in the other category.

Dr V Ramasubramanian, consultant, infectious diseases, Apollo Hospitals, explains that COVID-19 a cold virus attacks the receptors of smell and taste in the nose and mouth, causing loss of smell and taste. He says, “We are increasingly seeing these symptoms among those who are being diagnosed with COVID-19. The fact is that this is not specific to only COVIF-19, but in this season, if we see someone exhibiting these symptoms, it is almost sure that the person is infected with COVID-19. These could be only symptoms or could be displayed with sore throat and fever.”

Catching it on time helps cut transmission

Dr G Srinivas, professor and head, Department of Epidemiology, The Tamil Nadu Dr MGR Medical University, says that as per studies, the symptom is actually an early sign and if spotted on time, it can prevent transmissions. “This means it would show up during the early onset of infection. Though it is not an easy symptom to pick up, it could help restrict the spread, as the person reporting can be tested and can ensure early treatment, helping to break the chain of the virus at least one or two days early,” he says.

He cites ‘The Prevalence of Olfactory and Gustatory Dysfunction in COVID-19 Patients: A Systematic Review and Meta-analysis’ published in May 2020 that noted, “Olfactory ( sense of smell) and gustatory (sense of taste) dysfunction are common symptoms in patients with COVID-19 and may represent early symptoms in the clinical course of infection.

Increased awareness of this fact may encourage earlier diagnosis and treatment, as well as heighten vigilance for viral transmission. To our knowledge, this is the first meta-analysis to report on the prevalence of these symptoms in COVID-19 patients.”

An emerging symptom, are there more?

While the I can’t smell theory has been said to predict clusters where the cases are likely to shoot up in the coming days, researchers at Massachusetts General Hospital, health science company ZOE, King’s School of Biomedical Engineering & Imaging Sciences, Department of Twin Research & Genetic Epidemiology, and London Medical Imaging and AI Centre for Value-Based Healthcare have come up with an artificial intelligence diagnostic that can predict whether someone is likely to have COVID-19 based on their symptoms. The findings indicated that loss of taste and smell, known as anosmia, is a strong predictor of infection.

Dr N Kumarasamy, chief and director, VHS-Infectious Diseases Medical Centre, and director and site leader, Chennai Antiviral Research and Treatment (CART), Clinical Research Site of US National Institutes of Health, says that he has seen this symptom alone in a patient who was exposed to a positive patient, in his practise and she later tested positive, even as she didn’t have any other common symptoms like fever or sore throat. “I have also seen patients who have skin lesions on toes and hands—these are non-specific symptoms. COVID-19 as such doesn’t seem to have typical symptoms like viral fever,” he says.

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