Short-term and long-term impact of COVID-19 on multiple sensory systems

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Project Summary Since its outbreak in China in December 2019, the global impact of SARS-CoV-2 infection has been extraordinary, with over 350 million cases and more than 5.5 million lives lost (WHO Coronavirus Dashboard, Jan 2022). Despite various public health measures, such as social distancing, handwashing, face masking, and vaccination, infections in the US and the world continue in waves driven by new variants of concern (WHO). While the pandemic landscape has been constantly shifting, epidemiologists and public health experts increasingly project that the virus could eventually become endemic, especially with emerging zoological reservoirs. While information is still emerging, the full picture of neurological consequences of COVID-19 to broad sensory functions remains unclear, especially in the context of new variants, vaccination, prior infection, and ongoing treatment. For example, smell loss has been a hallmark symptom of COVID-19 (>80%) and can present in isolation (the only symptom of COVID-19) or precede the occurrence of other symptoms. Epidemiology studies have shown that smell loss is the most predictive symptom for COVID-19, better in identifying COVID-19 patients than cough, fever, headache, or other typical symptoms used to screen for COVID-19 in workplaces, schools, and health care settings. But with the emergence of Delta and Omicron variants and vaccination, it is unclear whether olfaction function is still severely impacted as in the early stage of the pandemic. Similarly, taste and chemesthesis (trigeminal) losses have been implicated but not fully differentiated from the flavor loss caused by retronasal smell losses. Sudden onset of hearing loss and dizziness have also been self-reported among COVID-19 patients, but current evidence for these are still limited, despite being in the 3rd year of the pandemic. In this study, Aim 1 will apply multidisciplinary methodologies to extensively capture and quantify the full impact of COVID-19 on broad sensory functions (smell, taste, chemesthesis, hearing, balance/vestibular function), with endemic viral upper respiratory infection (URI: cold, flu, etc.) as a comparison group. These tests will allow us to extensively explore and differentiate the impact of COVID-19 on multiple sensory functions and their association with the disease profile, such as severity, dominant variant at the time of infection, vaccination status, prior infections, and treatment received, with potential to characterize common and distinct factors to that of URI. Aim 2 will broadly assess the longitudinal time course of sensory loss and recovery among COVID-19 patients, with the expectation that recovery can vary depending on the system affected and the disease profile. Aim 3 will specifically focus on COVID-19 “long haulers”, patients who have persistent symptoms (>90 days), to examine the different characteristics in sensory losses and recovery during the prolonged disease phase. The outcomes of this study could importantly expand our understanding of the characteristics of broad sensory losses and their recovery among COVID-19 patients.