RT Journal Article SR Electronic T1 Serious vitamin D deficiency in healthcare workers during the COVID-19 pandemic JF BMJ Nutrition, Prevention & Health JO BMJ Nutrition FD BMJ Publishing Group Ltd SP e000364 DO 10.1136/bmjnph-2021-000364 A1 Takanori Funaki A1 Makiko Sanpei A1 Naho Morisaki A1 Tetsuya Mizoue A1 Koushi Yamaguchi YR 2022 UL http://nutrition.bmj.com/content/early/2022/01/03/bmjnph-2021-000364.abstract AB