As yet the evidence has been anecdotal, so a new group has been created, the Global Consortium of Chemosensory Research (GCCR), to work at pace to produce a ‘loss of smell and taste’ questionnaire and home testing kit for worldwide distribution. The UK lead for GCCR is Professor Barry Smith from the School’s Centre from the Study of the Senses (Censes), working in partnership with clinicians and sensory scientists. These include ear nose and throat (ENT) surgeon Dr Katherine Whitcroft, a member of the Centre and honorary fellow of the Institute of Philosophy.
The GCCR is a large global research consortium involving the world’s leading smell and taste scientists and clinicians. It is studying the loss of smell in coronavirus sufferers, to discover whether it is a marker of the virus in asymptomatic carriers, to distinguish this sudden loss of smell in Covid-19 from its presence due to blocked nose on flu and other respiratory illnesses, and to study the possible mechanisms of infection by the virus through the nose.
Professor Barry Smith says, “There are so many people reporting a sudden loss of their sense of smell, and they are surprised how much changes for them. They cannot smell the soap or shampoo they use and food and drink seem dull. It’s vital that we find out if this is an early warning symptom of Covid-19, and we want to find out the way in which the virus targets our sense of smell.”
He explains that in recent weeks a number of reports have come from China, South Korea, Germany, Italy, Iran and the UK, showing that loss of smell is a symptom of Covid-19. Reported rates of smell loss among those who tested positive for SARs-CoV-2 virus have been between a third and two-thirds. Published research has emerged from Italy here and Iran here showing a strong correlation between coronavirus and smell loss.
More significantly, evidence has emerged of sudden loss of smell among asymptomatic carriers of the virus, suggesting that if people experience a complete loss of smell, they should self-isolate. Chief medical officers acknowledge that we are seeing high incidence of smell loss among Covid-19 patients but still think more evidence is needed before declaring it key symptom. However, ENT-UK, the association of ear, nose and throat doctors and surgeons, have already stated that loss of smell and taste without other symptoms are a marker of Covid-19. See their statement here.
Consultant ENT specialists have seen a rapid rise in people reporting loss of taste and smell, says Professor Smith. So far, what we see is loss of smell and its impact on what we taste, although it is smell that is affected and not loss of taste itself.
People often confuse smell and taste not realising how much the former contributes to the latter and many who report that they can’t taste anything can be asked to perform the following home test. By putting a bit of salt on the tongue, or sugar or lemon juice, people can tell whether they can still taste these items. Most will report that they can, but they can’t taste much else. Now, they realise how much smell contributes to what we call tasting. It appears to be loss of smell, anosmia, or partial loss of smell, hyposmia, which most people with coronavirus are suffering. The sudden change in smell is striking to those who have experienced it. Food doesn’t seem to taste of much, and you won’t be able smell coffee, soap, hand sanitizer, or fresh laundry. A guide for patients has been provided by ENT-UK here.
The early indicators suggest – though we need more evidence – that the anosmia produced by SARs-Co-V-2 gradually subsides on average after 14 days later when smell is restored. People’s sense of smell does not return all at once. They rediscover the ability to smell one odour, then another, then another. With smell loss there is published research that smell training helps.
Regularly sniffing a number of familiar odours can improve patient’s olfactory function. For more information see Centre for the Study of the Senses’ partners, the charities AbSent and Fifth Sense.
“The priority is to get the GCCR questionnaire and home test to as many people as possible worldwide and we’ll be calling on a lot of countries to help us capture the data in this vast online citizen science project,” adds Professor Smith.