Younger people with COVID-19 are more likely to lose their sense of smell and taste than older patients, a new study has found.
Irish researchers examined 46 infected patients who were asked to assess changes to their smell, known as anosmia, and taste, known as ageusia.
About half of the participants experienced smell and taste dysfunction, which is a known symptom of the infectious disease.
But while older people are generally more vulnerable to other effects of COVID-19, younger patients were more likely to experience anosmia and ageusia, they found.
It’s possible that a loss of smell and taste in young patients may appear instead of more significant symptoms such as the cough and fever.
Despite this, people should self-isolate if they lose their sense of smell or taste because it is an officially recognised symptom of the disease.
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While older people are generally more vulnerable to other effects of COVID-19, the researchers found that younger patients were more likely to experience loss of smell and taste than older patients
‘These findings add to the body of evidence on the loss of smell and taste in COVID-19 patients and point to a higher frequency of these sense disturbances in younger patients,’ said lead author Colm Kerr at St. James’s Hospital Dublin.
It is believed loss of smell is caused by the virus infiltrating cells which give key structural support to sensory neurons.
On one single day at the end of March this year, the research team assessed the smell (olfactory) and taste (gustatory) functions of 46 COVID-19 patients.
This was measured on a five-point scale ranging from 1 (‘no change’) to 5 (‘very intense change’).
Nearly half of the patients – 48 per cent, or 22 out of 46 – reported some degree of olfactory sense loss, while more than half – 54 per cent, or 25 out of 46 – had gustatory sense loss.
Thirteen patients (28 per cent) reported a complete loss of sense of smell, eight (17 per cent) reported a complete loss of sense of taste and seven, or 15 per cent, reported total loss of both.
Graph shows patient’s reported scores of taste and smell disturbances, one being the lowest and 5 being the highest
Smell and taste scores were not significantly associated with gender, smoking status or presence of other illnesses.
However, the average age of patients with any degree of olfactory disturbance was significantly lower than patients without the symptom.
The average age for olfactory disturbance was 30.5 years, compared to an average of 41 years for those without.
Meanwhile, the average age of patients with any degree of gustatory disturbance was also lower than those without – 34 years old, compared to 40 years old.
Younger patients were disproportionately affected by smell, but not taste loss, the researchers found.
Loss of smell from COVID-19 does not appear to be permanent, scientists say, but can be an early symptom of the disease
A sign outside Watford General Hospital relating to the coronavirus pandemic. People should now self-isolate if they lose their sense of smell or taste because it is a definite symptom of coronavirus
The study is a retrospective analysis of a small cohort of patients with mild COVID-19, and therefore the results may not represent the presence of these features in patients with more severe cases of the disease.
‘As such, the prevalence of smell and taste disturbances should be further explored in larger patient cohorts and with varying spectra of COVID-19 severity,’ the team write in Infection Prevention in Practice.
What is anosmia?
Anosmia is the medical name for a condition in which someone suffers a complete or partial loss of their sense of smell and/or taste.
The most common single cause of the condition – temporary or permanent – is illnesses which affect the nose or sinuses, such as polyps which grow in the airways, fractured bones or cartilage, hay fever or tumours.
It is different to hyposmia, which is a decreased sensitivity to some or all smells.
Around 3.5million people in the UK are affected by the condition, along with nearly 10million in the US. It is surprisingly common and affects between three and five per cent of people.
Head injuries and nervous system diseases like Parkinson’s or Alzheimer’s may also contribute to the condition by damaging nerves in the nose which are responsible for detecting smells.
‘Further work should also investigate the prevalence of olfactory and gustatory disturbance in all patients being tested for COVID-19, in order to evaluate the diagnostic value of these features in predicting the presence of the disease.’
This is not however, the first study to draw a link between loss of taste and smell and younger patients.
An Italian study, published in Clinical Infectious Diseases, found that olfactory and taste disturbances were more frequent in younger patients.
Menni et al. also reported that smell and taste disturbances were predictive for the presence of COVID-19 in a UK-based study published in Nature Medicine, although they combined taste and smell together as a single variable.
The inability to smell and often taste may be the very first symptom of COVID-19 and can start within hours of infection.
The NHS lists ‘a loss or change to your sense of smell or taste’ as one of the three main symptoms of COVID-19, along with fever and a continuous cough.
‘This means you’ve noticed you cannot smell or taste anything, or things smell or taste different to normal,’ the NHS says.
One in ten people who lose their sense of taste and smell with the coronavirus may not get it back within a month, another study suggests.
Research on a small group of Italians who endured mild bouts of the disease found some still struggled to smell or taste a month after their illness.
The study, published in the journal JAMA Otolaryngology – Head and Neck Surgery, found 60 per cent of study subjects reported an alteration in their sense of smell and taste a month after they were diagnosed with COVID-19.
Loss of smell or taste were added to the UK’s list of coronavirus symptoms that require self-isolation as recently as May.
UK chief medical officers said at the time that anosmia – the scientific name for the loss of the senses – is clearly linked to the virus and should be treated with the same amount of caution as a fever or a new cough.
WE CAN LOSE SMELL AND TASTE ‘WITHIN HOURS OF INFECTION’
Data gathered by the organisation ENT UK, which represents ear, nose and throat specialists, suggests the inability to smell — and often taste — may be the very first symptom of COVID-19 and start within hours of infection.
Many people appear not to develop any further signs, making a full recovery without even realising they had the coronavirus. They are thought to be mostly healthy young adults whose immune systems react sufficiently to the virus to contain it within the nose, preventing it spreading to the lungs, where it can cause potentially fatal pneumonia.
As a result, warns ENT UK, some COVID-19 patients are not being identified as infected or advised to self-isolate – and may well be spreading the virus to others.
‘I have seen a huge increase in the number of patients attending my clinic with a sudden loss of smell,’ says Professor Nirmal Kumar, president of ENT UK and an ear, nose and throat specialist at Wrightington, Wigan and Leigh NHS Trust.
‘It’s up to about four patients a week, mostly under 40 and with no other COVID-19 symptoms. I usually see no more than one a month.’
Professor Kumar is advising patients with no obvious explanation for their loss of smell to self-isolate for at least seven days in case they have COVID-19, even though this is not the current government recommendation.
ENT UK has called on officials in the UK to recognise the symptoms as signs of coronavirus infection.
Past president of ENT UK, Dr Tony Narula, added: ‘Normally, when you get a cold or flu virus, you get a blocked nose and lose some smell because you can’t get air (which carries smells with it) into the nostrils,’ he says.
‘With COVID-19 it’s different. The virus seems to strike directly at the olfactory nerve at the roof of the nose, just between the eyes.
‘One reason so many people are suffering is that this nerve is not covered in protective tissue, so the virus attacks it and causes inflammation which stops smell signals reaching the brain.’