“This morning I saw two patients with parosmia,” Prof Kumar told the PA news agency.
“One said they could smell fish in place of any other scent, and the other can smell burning when there is no smoke around.
“Both are healthcare workers, and we think there is increased incidence in young people and also in healthcare workers because of exposure to the virus in hospitals.
“For some people, it is really upsetting them.”
Long COVID is a term to describe the effects of coronavirus that can continue for weeks or months beyond the initial illness.
Describing it as a “neurotropic virus”, Prof Kumar explained: “The virus is affecting the nerves in the roof of the nose – it’s like a shock to your nervous system, and the nerves aren’t functioning.”
Daniel Saveski, a 24-year-old banker living in London, said he lost his sense of taste and smell for two weeks after contracting coronavirus in March, and has been suffering with parosmia since.
Mr Saveski, from West Yorkshire, said strong-smelling things like bins now have a burning, sulphur-like odour, or smell “like toast”.
He added: “It’s lessened my enjoyment of food, and it’s a bit depressing not being able to smell certain foods.”
Lynn Corbett, an administrator for an estate agent, said she was “shocked” to wake up on her 52nd birthday in March with “absolutely no smell or taste”.
Ms Corbett, from Selsey in Sussex, said: “From March right through to around the end of May I couldn’t taste a thing – I honestly think I could have bitten into a raw onion such was my loss of taste.”
She said her sense of smell began to return in June, but “nothing smelled like it should”.
“Most things smelled disgusting, this sickly sweet smell which is hard to describe as I’ve never come across it before.”
The aroma of burnt toast and sulphur have also been reported
She said that despite previously being a “coffee addict”, the drink now smells “unbearable”, as do beer and petrol.
While she’s not sure whether she’ll ever regain her sense of smell, Ms Corbett said: “I’m okay with it, I just think myself lucky that if I did have coronavirus, which it looks like I did, then I haven’t been seriously ill, hospitalised or died from it like so many others.”
Charity AbScent, which supports people with smell disorders, is gathering information from thousands of anosmia and parosmia patients in partnership with ENT UK and the British Rhinological Society to aid the development of therapies.
They recommend anyone affected by parosmia to undergo “smell training”, which involves sniffing rose, lemon, clove and eucalyptus oils every day for around 20 seconds in a bid to slowly regain their sense of smell.