Background: Risk factors for severe coronavirus disease-2019 (COVID-19) infection include old age, chronic illness, and neurological conditions. In contrast, high vitamin D levels are known to augment immune activity and to reduce the severity of viral infections. Recently, a possible association between the likelihood of COVID-19 infection, COVID-19 severity, and vitamin D blood levels was reported.

Objective: To assess the possible association between vitamin D long-term supplementation and COVID-19 symptomatic severity and complications of COVID-19 infection in elderly psychiatric inpatients, a high at-risk group.

Methods: We conducted a retrospective case series study. Data of 14 elderly COVID-19 positive inpatients, presenting with dementia or schizophrenia and other medical conditions were extracted from medical records. All patients maintained a 800 IU daily dose of vitamin D prior to the infection.

Results: Most of the inpatients were asymptomatic or presented very few symptoms. No need for intensive care unit intervention or deaths were reported. Cognitive functioning of the patients remained unchanged.

Conclusions: Pre-existing vitamin D supplementation may reinforce immunity and reduce COVID-19 severity in elderly psychiatric inpatients.