Researchers call for loss of smell to be recognized globally as a symptom of COVID-19

Four out of five people experiencing the recent loss of smell and/or taste tested positive for COVID-19 antibodies—and of those who tested positive, 40 percent did not have cough or fever, reports a new study in PLOS Medicine by Prof. Rachel Batterham at University College London and colleagues.

COVID-19 can cause loss of taste and smell, but the prevalence of COVID-19 antibodies in people reporting these symptoms is unknown, and the significance of loss of smell and/or taste as a predictor of COVID-19 is not well understood. To estimate the seroprevalence of SARS-CoV-2 antibodies in people with acute loss of their sense of smell and/or taste, researchers enrolled 590 people self-reporting a loss of taste/smell in the previous month. Following verification of symptoms via a telemedicine consultation, 567 participants with smell and/or taste loss underwent a SARS-CoV-2 antibodies test.   

78% had SARS-CoV-2 antibodies, and participants with loss of smell were almost 3 times more likely to have SARS-CoV-2 antibodies compared to those with loss of taste, suggesting that a loss of smell is a highly specific symptom of COVID-19. Of the 78% of participants testing positive for antibodies, 40% had neither cough nor fever. While the study had limitations, such as the self-reporting of smell/taste changes and the lack of a control group, the researchers believe the evidence indicates that loss of smell should be taken into greater consideration in COVID-19 public health measures such as testing, case isolation, and treatment strategies. 

These findings also have significant implications for policy makers globally, as most countries do not currently recommend self-isolation and testing based on acute loss of smell/taste. This study suggests that an over-reliance on cough and fever as the main symptoms of COVID-19 may be flawed and that loss of smell needs to be urgently recognized globally as a key symptom of COVID-19.

Prof. Rachel Batterham, who led the study, said “Early self-recognition of COVID-19 symptoms by the members of the public, together with rapid self-isolation and PCR testing are vital in order to limit spread of the disease.  Currently, most countries around the world do not recognize sudden loss of smell as a symptom of COVID-19. 

78% of participants in our community-based study with sudden onset loss of smell or taste had SARS-CoV-2 antibodies. The vast majority had mild symptoms and 40% did not report having a fever or cough. Our findings suggest that people who notice a loss in their ability to smell every day house-hold odors such as garlic, coffee and perfumes should self-isolate and seek PCR testing. Loss of sense of smell needs to be recognized globally by policy makers as a key symptom of COVID-19.”

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Funding: This work was funded by the National Institute for Health Research (BRC751). https://www.nihr.ac.uk/ RLB, CGM, JM, and AC are funded by National Institute for Health Research grant RP-2015-06-005 (https://www.nihr.ac.uk/). RLB, NB, and JM are funded by the Sir Jules Thorn Trust Biomedical Research Award (https://julesthorntrust.org.uk/programmes/medical-research/the-sir-jules-thorn-award-for-biomedical-research/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. 

The National Institute for Health Research (NIHR) is the nation’s largest funder of health and care research. The NIHR:
Funds, supports and delivers high quality research that benefits the NHS, public health and social care
Engages and involves patients, carers and the public in order to improve the reach, quality and impact of research
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Invests in world-class infrastructure and a skilled delivery workforce to translate discoveries into improved treatments and services
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The NIHR was established in 2006 to improve the health and wealth of the nation through research, and is funded by the Department of Health and Social Care. In addition to its national role, the NIHR supports applied health research for the direct and primary benefit of people in low- and middle-income countries, using UK aid from the UK government. 

Competing Interests: The authors have declared that no competing interests exist. 

Citation: Makaronidis J, Mok J, Balogun N, Magee CG, Omar RZ, Carnemolla A, et al. (2020) 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 Med 17(10): e1003358. https://doi.org/10.1371/journal.pmed.1003358

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