COVID-19 survivors under age 40 who lose their sense of smell are more likely to regain it than older patients are, a new study suggests.
Researchers at Virginia Commonwealth University School of Medicine looked at data from nearly 800 people who said they had lost the ability to smell after contracting the virus.
Younger patients were 10 percent more likely to have regained the sense after recovery than middle-aged or senior adults.
What’s more, about one-quarter of those above age 40 reported having an abnormal sense of smell – either smelling things differently than they once did or a very muted sense once it returned.
A new study found that of COVID-19 survivors under age 40, 83.2% said they recovered their sense of smell in comparison with 74.5% of those above age 40 (file image)
In March 2020, the American Academy of Otolaryngology called on the Centers for Disease Control and Prevention (CDC) to add anosmia – the inability to smell – to its list of potential signs of coronavirus.
Early studies had established a link, such as one from April 2020 jointly conducted by Italy and the UK, which found that 64 percent of patients reported an ‘altered sense of smell or taste.’
At the time, the World Health Organization (WHO) said it was investigating a possible link between the two, but evidence was preliminary.
‘A loss of smell or a loss of taste is something that we’re looking into,’ Maria Van Kerkhove, the WHO’s technical lead for COVID-19 told reporters during media call in late March.
‘We are reaching out to a number of countries and looking at the cases that have already been reported to see if this is a common feature. We don’t have the answer to that yet.’
On April 27, the CDC added ‘new loss of taste or smell’ to its official list of symptoms.
However, it’s been unclear since the start of the pandemic which factors are linked to recovery of loss of smell.
A new study, published last month in the American Journal of Otolaryngology, set out to answer that question.
Researchers gathered data on 798 adult participants between April 11, 2020 and June 25, 2021 who reported loss of smell in a web-based nationwide survey.
Participants received follow-up surveys 14 days, one month, three months, and six months after they first enrolled.
They were asked to rate their sense of smell as ‘very good,’ ‘good,’ ‘poor,’ ‘very poor,’ or ‘absent’ prior to the pandemic and during each survey.
On day 14, only about half of participants – about 52 percent – rated their sense of smell as ‘good’ or ‘very good’ after losing it.
By the six-month follow-up, this percentage has increased to 79.5 percent, meaning most people who lose their sense of smell recover.
Researchers found that factors such as race, sex, smoking history, and blood type were not predictors of recovery of smell – but age was.
Of those under age 40, 83.2 percent said they recovered their sense of smell in comparison with 74.5 percent of those under age 40, which is a difference of 10 percent.
What’s more, 25.5 percent of patients above age 40 said their sense was ‘abnormal’ compare to 16.8 percent of adults under age 40.
The researchers are not sure why older patients are more likely to lose their sense of smell, but there are some theories.
People have a diminished sense of smell as they age with a loss of nerve endings and less mucus production in the nose, which may prevent smell from returning if it is lost during Covid infection.
Additionally, the lining of the nasal cavity may decline with age, leading to a higher risk of loss of smell in middle-age or as a senior citizen.
‘Although little is currently known about what factors may portend a higher or lower likelihood of olfactory recovery,’ the authors wrote.
‘This study suggests recovery of function is positively associated with younger age patients and those with nasal congestion.’