Associations between onychomycosis and COVID-19 clinical outcomes: a retrospective cohort study from a US metropolitan center

Little is known about the relationship of COVID-19 outcomes with onychomycosis. We investigated the relationship of onychomycosis with COVID-19 outcomes. A retrospective cohort study was performed on SARS-CoV-2 positive adult outpatients or inpatients who had onychomycosis and other skin diseases. Overall, 430 adults were identified with SARS-CoV-2 and a skin disease, including 98 with diagnosed onychomycosis. In bivariable logistic regression models, onychomycosis was associated with increased hospitalization {odds ratio(OR) [95% confidence interval (CI)]: 3.56 [2.18–5.80]}, initial inpatient vs. outpatient visits (OR [95% CI]: 2.24 [1.35–3.74]), use of oxygen therapy (OR [95% CI]: 2.77 [1.60–4.79]), severe-critical vs. asymptomatic-mild severity (OR [95% CI]: 2.28 [1.32–3.94]), and death (OR [95% CI]: 7.48 [1.83–30.47]) from COVID-19, but not prolonged hospitalization (OR [95% CI]: 1.03 [0.47–2.25]). In multivariable models adjusting for socio-demographics, comorbidities, and immunosuppressant medication use, the associations with onychomycosis remained significant for hospitalization, inpatient visits, oxygen therapy, severe-critical COVID-19. Onychomycosis was a significant independent risk factor for COVID-19 severity, hospitalization, and receiving supplemental oxygen therapy.