Malaysian COVID-19 Anosmia Study (Phase 2) - A Nationwide Multicentre Case-Control Study

The world is currently in the midst of the Coronavirus 2019 (COVID-19) pandemic that is caused by a novel coronavirus, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). According to published cohort studies on COVID-29 infected patients, the most prevalent symptoms consist of fever, dry cough, dyspnoea, sputum production, myalgia, arthralgia, headache, diarrhoea, and sore throat. Recently, there have been concerns of significant viral transmission through asymptomatic, pre-symptomatic or even mildly symptomatic patients.

There is increasing anecdotal evidence from patients and healthcare professionals highlighting isolated loss of sense of smell (anosmia) and taste disturbances (dysgeusia) as atypical symptoms of COVID-19 infection in otherwise asymptomatic patients. In parallel, expert statements from the British Association of Otorhinolaryngology-Head & Neck Surgery (ENT UK), British Rhinological Society, and the American Association of Otolaryngology-Head & Neck Surgery (AAO-HNS) have suggested that olfactory and taste disturbances could be a clinical feature of COVID-19 infection.

Rapidly emerging evidence from Europe, the United Kingdom and the United States have found olfactory and taste disturbances to be highly prevalent in patients diagnosed with COVID-19. In contrast, there is currently limited evidence from Asia on the prevalence of these symptoms in COVID-19 infection. Additionally, there is also limited evidence on the predictive value of screening for olfactory and taste disturbance in COVID-19 patients with subclinical symptoms.

The aim of this case-control study is to study the predictive value of screening for olfactory and taste disturbance in patients with COVID-19 infection in Malaysia. The cases will be selected from the cohort of COVID-19 positive patients recruited from participating Malaysian Ministry of Health-designated COVID-19 treating hospitals across the country (from Phase 1 of the Malaysian COVID-19 Anosmia Study). Controls will be recruited from healthy volunteers who will will answer the an online questionnaire to evaluate and characterise their olfactory and taste symptoms. This is the same questionnaire that is answered by the COVID-19 patients in case cohort.