Covid-19 and Vitamin D in Nursing-home

First epidemiological data about COVID-19 pandemic confirm that older adults are likely to experience severe and lethal forms of SARS-CoV-2 infection, in particular frail elderly living in nursing-homes. Vitamin D could be a biological determinant of COVID-19, as indicated by genomic-guided tracing of SARS-CoV-2 targets in human cells. Epidemiological observational data are necessary for better understanding the links between vitamin D supplementation and COVID-19 outcomes, in particular in nursing-homes (in which the risk of hypovitaminosis D is very high).

The investigators had the opportunity to use information collected in a French middle-sized nursing-home affected by COVID-19 in March-April 2020, to determine whether recent vitamin D3 supplementation was associated with the prognosis of COVID-19 in residents infected with SARS-CoV-2. As recommended in French nursing-homes, all residents are systematically and regularly supplemented with bolus vitamin D3 (every single, 2 or 3 months, depending on residents).

The main objective of this study is to determine whether bolus vitamin D3 supplementation taken during or in the month before COVID-19 was effective in improving survival among frail elderly nursing-home residents infected with COVID-19 compared to those having received supplementation longer ago.

The secondary objective is to determine whether bolus vitamin D3 supplementation taken during or in the month before COVID-19 was effective in limiting the clinical severity of the infection according to the World Health Organization's Ordinal Scale for Clinical Improvement (OSCI) for COVID-19 compared to those having received supplementation longer ago.