Sudden loss of taste or smell should be considered a global criterion for self-isolation, testing, and contact tracing for COVID-19, UK-based researchers say.
A new study by UCL and University College London Hospitals NHS Foundation Trust (UCHL), London, UK, found that four out of five people who experienced anosmia tested positive for COVID-19 antibodies, making it a “highly reliable” virus indicator.
It is the first study to accurately establish the proportion of those who had experienced loss of smell and or taste as having COVID-19.
Lead author Professor Rachel Batterham, of UCL Medicine and UCLH, said: “As we approach a second wave of infections, early recognition of COVID-19 symptoms by the public together with rapid self-isolation and testing will be of vital importance to limit the disease’s spread.
“While people in the UK who experience sudden onset loss of smell or taste are advised to self-isolate and seek a test, at a global level few countries recognise this symptom as a COVID-19 indicator: most focus on fever and respiratory symptoms.
“Our findings show that loss of smell and taste is a highly reliable indicator that someone is likely to have COVID-19 and if we are to reduce the spread of this pandemic, it should now be considered by governments globally as a criterion for self-isolation, testing, and contact tracing.”
The cohort study, published in the latest PLOS Medicine, assessed health data from primary care centres in London and the research team found that 78% of people who reported sudden loss of smell and/or taste at the height of the pandemic had SARS-CoV-2 antibodies. Of these people, 40% did not have a cough or fever.
The study involved 590 participants, all of whom were enrolled 23 April and 14 May 2020 via a web-based platform. They answered questions about loss of smell and taste and other COVID-19–related symptoms.
567 went on to have a telemedicine consultation with a healthcare professional who confirmed the history of their symptoms and supervised a test to establish if they had SARS-CoV-2 antibodies.
The researchers calculated that 77.6% of the 567 participants with smell and/or taste loss had SARS-CoV-2 antibodies. Of these 39.8% had neither cough nor fever, and participants with loss of smell were three times more likely to have SARS-CoV-2 antibodies, compared with those with loss of taste.
Professor Batterham added: “Our research suggests a key public health message should be: people who notice a loss in their ability to smell everyday household odours such as garlic, onions, coffee, and perfumes should self-isolate and seek a coronavirus PCR swab test.”
Makaronidis J, Mok J, Balogun N et al. Seroprevalence of SARS-CoV-2 antibodies in people with an acute loss in their sense of smell and/or taste in a community-based population in London, UK: An observational cohort study. PLOS Medicine 1 October 2020; doi: 10.1371/journal.pmed.1003358
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