Document Type : Original Article
Authors
1
Department of Biology, College of Education-Qurna, University of Basrah, Basra, Iraq
2
Department of Environmental and Pollution Technical Engineering, Basrah Engineering Technical College, Basra, Iraq
3
College of Health and Medical Technologies, Southern Technical University , Basrah, Iraq
4
Centre for Biotechnology, Maharshi Dayanand University, Rohtak, Haryana, India
Abstract
Introduction: Host innate mucosal immunity may influence the clinical course of SARS-CoV-2 (COVID-19) infection. Extraoral bitter taste receptors, particularly T2R38, are expressed in the respiratory epithelium, where they stimulate nitric oxide production and promote mucociliary clearance. This study examined cross-sectional associations between phenylthiocarbamide (PTC) taste sensitivity and self-reported COVID-19 history, symptom phenotypes, particularly dry versus productive cough, clinical outcomes, and vaccination status in young adults.
Materials and Methods: In this cross-sectional observational study (n = 324 young adults), standardized PTC taste strips were used to classify participants as tasters (75.3%) or non-tasters (24.7%). Retrospective infection history, symptom patterns, clinical outcomes, and vaccination status were analyzed using chi-square tests, independent-samples t-tests, and multivariable logistic regression adjusted for age, sex, smoking status, and vaccination status.
Results: Non-tasters exhibited higher infection rates (70.0% vs. 41.8%, p = 0.0003) and higher odds of acquiring COVID-19 (OR = 2.84, p = 0.0002), alongside active smoking (OR = 1.67, p = 0.042). Among infected participants, non-tasters experienced a greater symptom burden (6.3 ± 2.1 vs. 4.1 ± 1.6, p < 0.001), a predominantly productive cough with phlegm (57.1%), and increased hospitalization (25.0% vs. 8.8%, p = 0.004), oxygen requirement (19.6% vs. 4.9%, p = 0.002), and complications (39.3% vs. 17.6%, p < 0.001). Vaccination conferred greater absolute risk reduction against infection in tasters (53.9%) than in non-tasters (17.8%; p = 0.009).
Conclusions: The PTC non-taster phenotype was cross-sectionally associated with increased odds of COVID-19 infection, greater symptom burden, and a distinct productive cough presentation in this young adult cohort. Although these observational findings are consistent with hypothesized mucosal innate immune mechanisms, prospective longitudinal studies incorporating comprehensive comorbidity controls and direct mucosal bioassays are needed to establish true clinical predictive utility.
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