Table 2. Eligible studies.

Author	Reference	Cohort	No. of Patients	Laboratory Results Recorded Pre-/Post-Infection	Mortality	Vitamin D Level [ng/mL]
Ahmad et al., 2021	[142]	19 European countries	448,785,546	Up to 10 months in advance	Refer to source study
Angelidi et al., 2021	[159]	<30 ng/mL	79	Within 1 day after admission	25.30%	NR a Median (IQR): 28 ng/mL (16.80–39.00 ng/mL)
		≥30 ng/mL	65		9.20%
Charoenngam et al., 2021	[160]	<20 ng/mL	96	Up to 1 year in advance	14.58%	NR a
		20–30 ng/mL	91		16.48%
		≥30 ng/mL	100		12.00%
Gavioli et al., 2021	[126]	Deficient	177	Up to 3 months in advance	29.00%	14.00 31.00
		Sufficient	260		31.00%
Susianti et al., 2021	[161]	<49.92 nmol/L	42	Within 1 day after admission	45.00%	8.00 28.40
		≥49.92 nmol/L	8		42.00%
Szeto et al., 2021	[127]	<20 ng/mL	35	Up to 12 months in advance	23.00%	16.00 32.00
		≥20 ng/mL	58		24.00%
Vanegas-Cedillo et al., 2021	[115]	≤20 ng/mL	251	Within 1 day after admission	23.50%	NR a Mean ± SD 21.78 ± 9.01 ng/ml
		>20 ng/mL	300		19.00%
Vassiliou, 2020	[120]	≤19.9 ng/mL	32	Within 1 day after admission	25.00%	NR a
		20–29.9 ng/mL	7		14.30%