Irish researchers examined more than 40 infected patients who were asked to assess changes to their smell and taste for potential signs of anosmia.

About half of the participants experienced smell and taste dysfunction، which is a known symptom of the infectious disease، the Daily Mail reported.

But while older people are generally more vulnerable to other effects of COVID-19، younger patients were more likely to experience olfactory sense loss، they found.

It’s possible that a loss of smell and taste in young patients may appear instead of more significant symptoms such as cough and fever.

Despite this, person should self-isolate if they lose their sense of smell or taste because it is an officially-recognized symptom of the disease.

‘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 the 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 percent, or 25 out of 46 – had gustatory sense loss.

Thirteen patients (28 percent) reported a complete loss of sense of smell، eight (17 percent) reported a complete loss of sense of taste and seven، or 15 per cent، reported total loss of both.

Smell and taste scores were not significantly associated with gender، smoking status or the 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.

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 writes in Infection Prevention in Practice.

‘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 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 percent 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 was 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.