Vitamin D3and gargling for the prevention of upper respiratory tract infections: a randomized controlled trial

BMC Infectious Diseases

Table 2 Frequency, severity, duration and viral load (log viral copies/mL) associated with URTI according to vitamin D allocation

Outcome measure	Clinical URTI				Laboratory confirmed URTI
Outcome measure	Vitamin D (n = 258)	Placebo (n = 234)	Effect measure (95% CI)	P value	Vitamin D (n = 256)	Placebo (n = 233)	Effect measure (95% CI)	P value
Imputed URTI episodes, No. (%)	91 (30.3)	114 (38.0)	^*RR:0.80 (0.63-1.02)	0.08
Complete case URTI episodes, No. (%)	70 (27.1)	80 (34.2)	^*RR:0.79 (0.61-1.03)	0.09	26 (10.2)	44 (18.9)	^*RR:0.54 (0.34-0.84)	0.007
^€Viral load, mean (SD)					5.51 (1.6)	6.40 (1.2)		0.036
^†Symptom duration, mean days, (SD)	6.0 (1.6)	6.2 (1.3)	^*HR: 1.32 (0.59-2.90)	0.49	5.8 (1.5)	6.2 (1.2)	^*HR: 1.30 (0.49-3.48)	0.59
^†Symptom severity, mean (SD)	218.6 (124.0)	199.8 (108.1)		0.41	229.7 (110.3)	181.5 (91.9)		0.09

RR: relative risk, HR: Hazard ratio.
^*The Poisson and Cox regression models were adjusted exclusively for randomization strata: vitamin D allocation, gargling allocation, year of participation and type of housing.
^€Viral load was measured as log₁₀ viral copies/mL.
^†Symptom duration and severity was measured only in participants who self-reported illness (ie. not for adjudicated events), n = 106. For clinical URTI, n = 53 in each of the vitamin D and placebo groups. For laboratory confirmed URTI n = 22 and n = 34 in the vitamin D and placebo groups respectively.

ISSN: 1471-2334