Although a loss of taste or smell (anosmia) has been added to the list of COVID-19 symptoms, a new study conducted before anosmia was added to the list, serves to highlight the importance of these symptoms.
The results showed that individuals who experience loss of smell were three times more likely to have COVID-19 antibodies than those with isolated taste loss. In this newly published study, researchers from University College London, recruited individuals between April and May 2020, when anosmia was not recognised as a symptom of COVID-19. Adults registered with four primary care centres in London were sent a text message asking whether their sense of taste or smell had reduced in the last month. Those answering yes were directed to an online questionnaire which collected demographics and other information and were sent a point-of-care antibody testing kit. Participants then held a video consultation with a healthcare professional who supervision collection of a whole blood sample from a finger-prick test.
A total of 33,650 text messages were sent and 590 participants recruited, of whom 567 (96%) had an antibody test and the mean age of the sample was 39.4 years (69.1% female). Among the 567 individuals, 78% of tested positive with 93.4% reporting either a complete or partial loss of a sense of smell and 90.2% either a complete or partial loss of taste. Interestingly, 40% of those testing positive had neither a cough or fever. In regression analysis, participants with a loss of smell alone were nearly three-times more likely than those with isolated taste loss to have COVID-19 antibodies (adjusted odds ratio, OR = 2.72, 95% CI 1.37 – 6.36, p < 0.001). Moreover, those with a combined loss of smell and taste were four-times (adjusted OR = 4.11, 95% CI 2.24 – 7.08, P < 0.001) to have COVID-19 antibodies.
Commenting on their findings, the authors noted that loss of smell was a highly specific symptom for COVID-19 and that this alone should be used as a criterion for self-isolation.
Makaronidis J 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 Med 2020;17(10): e1003358. https://doi.org/10.1371/ journal.pmed.1003358