Smell loss was a defining symptom of Covid, and for some people, a curse. Most people regain their sense of smell as their infection fades, but some never recover. It means not being able to tell if milk is off, if there’s a gas leak or what your newborn baby smells like.
But for victims of anosmia and its crueller sibling, parosmia, where ordinary smells are transformed into the stench of rotting flesh or sewage, there is new hope. Researchers have discovered that a simple procedure can help people recover their sense of smell years after losing it to viral infections such as Covid, or even decades later.
The first patient in the UK began receiving treatment this month and doctors hope the process could be easily rolled out across the NHS.
Chrissi Kelly is the first patient in the UK to receive the treatment, which consists of injections of platelet-rich plasma (PRP) from her own blood, prepared by using a centrifuge to separate the platelets from red and white blood cells.
“It’s amazing to be able to say ‘there’s a treatment’, because for years that was just off the table,” Kelly said. “And it’s thrilling to be asked to be the first one to receive it.”
Kelly lost her sense of smell after developing sinusitis in 2012, and describes anosmia as “like a bereavement”. After three months she began to hallucinate smells, a condition known as phantosmia, then developed parosmia.
The only help she could find was research that suggested she could retrain her sense by inhaling known smells such as coffee and lavender. The condition was so little known that Kelly decided to set up a charity, AbScent, to offer support to other sufferers and make other smell-training kits.
The Covid pandemic changed everything, with millions of people around the world losing their sense of smell, including Katherine Ryan, the comedian, who said the disorder made her feel “helpless”. AbScent went from 1,500 members in its support group to 95,000 at the same time as its income from the smell-training kits disappeared when cheaper competitors emerged. She closed the charity last year.
But the pandemic also sparked a new wave of research. Prof Zara Patel, director of endoscopic skull base surgery at Stanford University, had been examining anosmia for some time and spotted a neurology paper that suggested PRP might help regenerate nerves.
This is important because of the reason Covid affects smell – the SARS-CoV-2 virus binds to cells around the olfactory nerve at the top of the nose.
“The way that the olfactory system and olfactory nerve works is unique in all the other cranial nerves,” Patel told the Observer. “None of the other cranial nerves have the ability to regenerate, but the olfactory nerve does.”
So if PRP could help the olfactory nerve regenerate, it might relieve anosmia. Patel set up a series of randomised control trials – easier to recruit after Covid – and found that PRP worked better than a placebo after three months and the effect was greater after 12 months. In one case, a 73-year-old man recovered his smell 45 years after losing it.
Patel’s work impressed Prof Claire Hopkins, a former president of the British Rhinological Society and professor of rhinology at King’s College London who practises at Guy’s hospital in London. She was one of the first people to identify a link between Covid and anosmia and had been investigating other treatments such as steroids.
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“I’ve been hesitant before because I know many patients are desperate and will try anything,” Hopkins said, mentioning folk remedies such as burning oranges that are ineffective.
“[The evidence] is significant to a point that I feel I should be offering this to my patients, and it is a relatively minimally invasive procedure. The risks are small, so I think it is something I can now offer. I will look to try to set this up within the NHS. PRP is used within the NHS for other things, so I’m hopeful we will be able to offer it.”
Because PRP is made with centrifuges that are already being used in hospitals, and uses a patient’s own blood, there are fewer regulatory hurdles than other medical procedures. Hopkins and other ear, nose and throat teams need to get approval for the procedure from their hospital boards.
Kelly needs to have two further PRP injections over the next three months to complete the treatment. She is cautious about whether she can already sense any effects.
“I’m probably the most acute observer of my own sense of smell,” she said, referring to her years of smell training. “I still can’t eat onions. I’m great with coffee, but there are other things like roasted meat I really don’t enjoy as much as I used to.
“When I step out of the house in the morning, I will recognise that I’m getting some kind of feedback on what the time of year is and that sort of thing. It’s not always easy for me to say I smell something specific, but I’m always aware of that.
“And the other day, I stepped out of my house, and I’m thinking to myself, ‘Oh gosh, that smells good.’ And before I turned around, I thought to myself, ‘That smells like winter-flowering jasmine.’ And it was.”
