Millions still without sense of smell or taste after Covid-19

Still struggling with your sense of smell after a bout with Covid-19? You are far from alone.

A new analysis indicates that about 5% of patients with confirmed cases of Covid-19 – about 27 million people worldwide – have experienced a long-term loss of smell or taste.

In the analysis published Wednesday in The BMJ (the British Medical Association’s peer-reviewed medical journal)And the The researchers evaluated 18 previous studies of loss of smell and taste across several continents and in different population groups. About three-quarters of people with loss of taste or smell regain those senses within 30 days.

Recovery rates have improved over time, but about 5% of people report “persistent dysfunction” six months after contracting Covid-19.

The analysis suggests that loss of smell and taste may be a long-term concern that requires more research and health resources for patients with long-term symptoms.

Stanford rhinologist Dr. Zara Patel, who was not involved in the BMJ research, said loss of smell is associated with higher mortality rates in older adults, and has been shown to have significant effects on people’s emotional and psychological health.

“Having these millions now around the world with a reduced ability to smell – it may simply be a new public health crisis,” Patel said.

Loss of smell was one of the most visible signs of Covid-19 in the early days of the pandemic.

“You can track the epidemic all over the world” by analyzing Google searches about smell loss, Patel said.

The BMJ analysis gives an extensive review of odor studies around the world and over time. Data from approximately 3,700 patients were included in the analysis.

All studies from North America, Europe and Asia were included in the analysis, which indicated that women are less likely to regain their senses of smell and taste than men. Patients with nasal congestion were also less likely to recover.

The analysis showed steady increases in the proportion of patients who regained their sense of smell over time. After 30 days, about 74% of patients had recovered; After 90 days, this number had reached 90%. After six months, about 96% of patients said they were able to smell again.

Scientists are beginning to understand how Covid-19 affects the function of smell.

Corona virus often causes swelling of the olfactory fissures, the passages in the upper part of the nasal cavity. Humans perceive the sense of smell and the flavor of processing beyond basic tastes such as sour or bitter.

The researchers believe that the virus does not initially infect the olfactory neurons, but instead attaches to the supporting cells, helping the neurons provide a signaling pathway.

Patients who experienced loss of smell after Covid-19 made up a unique subgroup, said Dr. Aria Jafari, a rhinologist at UW Medicine’s Sinus Center in Seattle, who was not involved in the new analysis. “They tend to get better rather quickly, which makes sense based on the affected cells.”

Jafari said about half of his smell-deprived patients will likely have had Covid-19 at some point. Many suffered dramatic effects on their well-being due to the loss.

“They tend to be dumbfounded about losing their sense of smell. It’s an important part of every day and what makes us human,” said Al-Jaafari, adding that he treats a professional chef, chocolatier and others whose livelihoods depend on their lives. The ability to determine the smell and flavour. “The most common thing I hear is that it leads to social isolation and a feeling of disconnection from the world and society as they know it. And that can be really upsetting.”

Jafari said many patients also describe a “can be painful” transition period in which their sense of smell for things that aren’t there — such as burning rubber or smoke — return or experience abnormally foul smells.

Jafari said that people who are unable to smell or feel flavors can have higher rates of mental illness, depression and anxiety. In extreme cases, Jaafari said he treated a malnourished patient who had lost his senses of smell and taste.

Smell is central to the way we interact with each other and make our way in the world, says Patel, dictating your “first impressions of other people, the people we choose for sexual encounters or for lifelong partners.” Studies show that cues from smell can subconsciously influence people’s attraction to others based on the genes behind them.

The analysis is based on studies using patients’ self-reported data. That could understate the true value of the scent imbalance and skew some research results because sometimes people aren’t able to realize how much sensitivity they’ve lost, Patel said.

The study authors agreed.

Professor Song Toh, study author and Chair of Otolaryngology-Chairman of Otolaryngology, wrote: “Several previous studies have shown that objective smell testing can identify significantly more people with anosmia than if we asked them to. Report themselves. and Neck Surgery at Singapore General Hospital, via email. “The true number of people affected is likely to be much higher than our estimates.”

Patel suspects that the true rate of dysphoria among those who have experienced Covid-19 may be higher than 20%. Women may not be more likely to suffer from recovery, but they are more aware of the prolonged deficit in their ability to smell.

“Women in general have, on average, a sharper sense of smell than men,” Patel said. “We know that people with a more intense sense of smell and taste are more likely to perceive when they have experienced a loss and are more likely to seek care in the event of a loss.”

Jafari said the BMJ’s analysis generally tracks his clinical experience and observations of patients’ recovery.

“It’s a good idea to collect data from around the world to better understand what’s going on and extract some variance from these patient group or institution-specific analyzes,” Jafari said. “It increases the level of evidence, in general, to support what we, as sinus surgeons, see in our offices.”

Patel said initial versions of the omicron variant appeared to affect the sense of smell less than previous waves of Covid-19.

But the latest variant, BA.5, could reverse that trend.

“We don’t have enough data yet to know for sure,” Patel said. “Now, in my clinic, I’m starting to see a slight rise again.”

Treatments are available for people who have lost their sense of taste and smell due to Covid-19.

Olfactory training — in which patients smell essential oils like lemon, clove, eucalyptus and rose twice a day to stimulate different types of neurons — can re-teach the brain to recognize different scents. Doctors often prescribe a steroid wash for the sinuses to reduce inflammation and aid in training.

Some emerging evidence suggests that omega-3 fatty acid supplementation can be beneficial for patients with olfactory dysfunction.

Patel et al. are exploring other treatments, including intranasal injection of platelet-rich plasma and electrical stimulation.

Patel said she hopes that research funding and public interest in malfunctions of smell and taste will continue to grow so that researchers can dive deeper and unlock new treatments.

“The orphan feeling was Cinderella,” Patel said before the pandemic. “Only after millions of people or their loved ones were affected, did people begin to understand the tremendous effects of smell and taste on your quality of life.”

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