Study	Reason for exclusion
Beigmohammadi 2020	combination of vitamin D with other treatments
CTRI/2020/06/026191	prevention
Euctr2020‐001363‐85‐dk	prevention
Euctr2020‐001903‐17	combination of vitamin D with other treatments
IRCT20200319046819N1	combination of vitamin D with other treatments
IRCT20200705048013N1	combination of vitamin D with other treatments
NCT04351490	study withdrawn: the study stopped early, before enrolling its first participant. Combination of vitamin D with other treatments
NCT04395768	combination of vitamin D with other treatments
NCT04399746	combination of vitamin D with other treatments
NCT04407286	single‐arm study
NCT04476680	prevention
NCT04482686	combination of vitamin D with other treatments
NCT04483635	prevention
NCT04507867	combination of vitamin D with other treatments
NCT04535791	prevention
NCT04565392	combination of vitamin D with other treatments
NCT04579640	prevention
NCT04596657	prevention
NCT04780061	combination of vitamin D with other treatments
Nogues 2021	non‐randomised study; paper removed from preprint server quote: "due to concerns about the description of the research in this paper"