Calcitriol, the active form of vitamin D, is a promising candidate for COVID-19 prophylaxis

Mok, Chee Keng; Ng, Yan Ling; Ahidjo, Bintou Ahmadou; Hua Lee, Regina Ching; Choy Loe, Marcus Wing; Liu, Jing; Tan, Kai Sen; Kaur, Parveen; Chng, Wee Joo; Wong, John Eu-Li; Wang, De Yun; Hao, Erwei; Hou, Xiaotao; Tan, Yong Wah; Mak, Tze Minn; Lin, Cui; Lin, Raymond; Tambyah, Paul; Deng, JiaGang; Hann Chu, Justin Jang

COVID-19, the disease caused by SARS-CoV-2 (1), was declared a pandemic by the World Health Organization (WHO) in March 2020 (2). While awaiting a vaccine, several antivirals are being used to manage the disease with limited success (3, 4). To expand this arsenal, we screened 4 compound libraries: a United States Food and Drug Administration (FDA) approved drug library, an angiotensin converting enzyme-2 (ACE2) targeted compound library, a flavonoid compound library as well as a natural product library. Of the 121 compounds identified with activity against SARS-CoV-2, 7 were shortlisted for validation. We show for the first time that the active form of Vitamin D, calcitriol, exhibits significant potent activity against SARS-CoV-2. This finding paves the way for consideration of host-directed therapies for ring prophylaxis of contacts of SARS-CoV-2 patients.