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Infectious Diseases

Updated 30 June 2020

How common is losing taste and smell among Covid-19 patients? Scientists took a closer look

More evidence shows that this symptom could be pivotal in the early detection of coronavirus.

  • A study found that over half of Covid-19 patients reported reduced levels of taste during their illness 
  • Around 41.7% had reduced smell, while 40% in total experienced a loss of both 
  • Stuffy noses were present in only about 7.8% of the subjects at the onset of the disease 


While scientists have confirmed that a loss of taste and smell is one of the major symptoms of Covid-19, a new study looked at how frequent this symptom presented in positive cases. 

Published in JAMA Network, researchers from the Humanitas Clinical and Research Centre in Milan, Italy, analysed the feedback from 204 patients diagnosed with the coronavirus and who were able to respond to a questionnaire. 

READ: Loss of smell, taste - researchers think these symptoms may help better screen for Covid-19

About 55.4% reported a reduced sense of taste, while 41.7% had a reduced sense of smell. 

More prevalent in women

In total, 40.2% reported a reduction of both senses. However, only 7.8% of the cases reported a stuffy or runny nose – an uncommon symptom of Covid-19. 

These symptoms were, therefore, more frequent than all the other major symptoms, except for coughing. 

They also found that the loss of smell and taste was more prevalent in women, and patients with a severe case of these symptoms were younger than those who had no or mild symptoms. 

No link was, however, found between smoking and the loss of these senses.   

Alongside its frequency, researchers also noted that symptoms relating to taste and smell presented themselves between four and seven days before diagnosis, highlighting their importance as an early indicator of the disease. 

Smell may never return

Some of the limitations of the study include the lack of a control group with no symptoms of the virus, and that the data relied on self-reporting and not physical check-ups by healthcare workers. 

ALSO READ: Loss of smell and taste might be long-term for some Covid-19 survivors

Just like the researchers from King’s College London urged in a letter earlier this month, this study concludes that taste and smell symptoms should be more prominent in the screening process for the coronavirus. 

They especially advise general practitioners to look out for these symptoms and recommend quarantine as soon as they are detected, before a test can be taken. 

The effect of coronavirus on the olfactory pathways has been well-documented since researchers first start noticing it. It was mostly found in mild to moderate Covid-19 cases. There is also the risk that some patients may never recover their sense of smell after clearing the virus. 

Some experts have also suggested that "smell the difference" tests could be used in public spaces in order to discover unsuspected cases and help curb the spread. 

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