Table 1. Search strategy.

SourceSearch StrategyTime Frame
PubMedCOVID-19 Search String from [153] AND (“vitamin d” or “d3” or “25(OH)D” or “25-hydroxyvitamin D”)1 November 2019–27 March 2021
https://c19vitamind.com (accessed on 27 March 2021)Restriction to category “Levels”1 November 2019–27 March 2021