Omicron and other more recent variants of Covid-19 are less likely to have loss of smell and taste as indicators of infection in patients, according to new research.
Those infected with the Omicron variant are less likely to develop smell and taste loss compared to those who contracted the Delta and other earlier Covid variants, pointed out a study published this month in the journal Otolaryngology — Head and Neck Surgery.
The chances of the symptoms of smell and taste loss occuring for the Omicron variant were just 17 per cent, compared to much higher rates of these symptoms during the early phase of the pandemic in 2020.
Rates of these symptoms were greater for the Delta and Alpha variants, at 44 per cent and 50 per cent respectively, said researchers, including those from the Virginia Commonwealth University (VCU) in the US.
“We now know that each variant has a different risk factor for associated smell and taste loss and have reason to believe that newer variants are less likely to impact smell and taste,” Daniel Coelho, lead author of the study from the VCU School of Medicine, said in a statement.
“Loss of smell and taste is still a good indicator of a Covid-19 infection, but the reverse is no longer true. Do not think you are Covid-negative just because your sense of smell and taste is normal,” explained Dr Coelho, an ear, nose and throat specialist.
A national database of over 3.5 million cases of patients from the US who tested positive for Covid since the onset of the pandemic was assessed by researchers for the study.
They identified 6-week periods where cases were highest for each variant studied and then compared how many patients were diagnosed with smell and taste loss in these timeframes.
“Patients infected with more recent variants are at a significantly lower risk of developing associated chemosensory loss,” they wrote in the study.
Scientists believe comparing the variants and their effects could offer a clue in figuring out what part of the molecular structure of the virus causes such olfactory declines.
“Unlocking what causes smell and taste loss in the first place will help us better determine how to treat it,” Dr Coelho said.
In further research, scientists hope to study the recovery time from smell and taste loss from different variants and understand if vaccination status plays a role in the reduced rates of these symptoms.
They are also attempting to develop an implant device – similar to a cochlear implant that restores hearing for those with hearing loss – to restore the sense of smell.
“This is not just about being able to enjoy a fine bottle of wine again; it’s about safety and preserving your quality of life. Our research shows that more than 50 per cent of people suffering from smell and taste loss have reported feeling depressed,” Dr Coelho said.
“Patients with smell loss also have a higher rate of dementia. Fewer people experiencing these symptoms means fewer people being impacted by mood changes and cognitive problems,” he added.