Role of vitamin D in COVID-19 and other viral infections

Table 3 Effect of vitamin D levels on viral infections according to age, gender and systemic conditions

Ref.	Age group	Gender	Preexisting conditions	Results
Martineau et al[43], 2017	0–95 yr	Both genders	Asthma, COPD	Vitamin D supplementation is effective in reducing the risk of acute respiratory infections
Ginde et al[9], 2009	≥ 20 yr	Both genders	Chronic diseases (DM, HT)	Vitamin D deficiency is associated with the prevalence of upper respiratory tract infections
Sabetta et al[44], 2010	20–89 yr	Both genders	Chronic diseases	The risk of respiratory tract infection is reduced in individuals with serum 25(OH)D levels above 38 ng/mL
Cannell et al[7], 2006	0–90 yr	Both genders	Various health conditions	Vitamin D deficiency may increase susceptibility to influenza and respiratory infections
Laaksi et al[45], 2007	18–28 yr	Male	Healthy individuals	Vitamin D supplementation may reduce incidence of respiratory infections
Urashima et al[46], 2010	6–15 yr	Both genders	Healthy children	Vitamin D supplementation is effective in reducing the incidence of influenza A
Berry et al[47], 2011	≥ 65 yr	Both genders	Chronic diseases	Vitamin D deficiency is associated with risk of respiratory infections
Murdoch et al[48], 2012	50–84 yr	Both genders	Chronic diseases (COPD)	Vitamin D supplementation has no protective effect on respiratory infections
Jolliffe et al[49], 2020	0–95 yr	Both genders	Asthma, COPD	Vitamin D supplementation is effective in reducing the risk of acute respiratory infections
Camargo et al[50], 2012	3–24 yr	Both genders	Healthy children	Vitamin D deficiency may increase risk of acute lower respiratory tract infections
Hollams et al[51], 2011	0–10 yr	Both genders	Asthma, allergy	Vitamin D deficiency is associated with asthma and respiratory infections
Majak et al[52], 2011	5–18 yr	Both genders	Asthma	Vitamin D supplementation may reduce infection frequency in children with asthma
Esposito et al[53], 2013	0–16 yr	Both genders	Healthy children	Vitamin D deficiency may increase risk of respiratory infections
Thornton et al[54], 2014	18–45 yr	Both genders	HIV positive individuals	Vitamin D deficiency is associated with risk of respiratory infections
Belderbos et al[55], 2011	0–1 yr	Both genders	Healthy babies	Vitamin D deficiency may increase the risk of respiratory syncytial virus bronchiolitis
McNally et al[56], 2009	0–17 yr	Both genders	Chronic diseases	Vitamin D deficiency associated with respiratory tract infection in intensive care
Le Goaziou et al[57], 2011	0–16 yr	Both genders	Healthy children	Vitamin D deficiency is associated with risk of upper respiratory tract infections
Liu et al[58], 2020	0–18 yr	Both genders	Chronic diseases (asthma, COPD)	Vitamin D deficiency associated with risk of viral respiratory infections
Grant et al[59], 2009	0–95 yr	Both genders	Various health conditions	Vitamin D deficiency may increase risk of influenza and pneumonia
Aloia et al[60], 2007	18–45 yr	Both genders	HIV positive individuals	Vitamin D deficiency is associated with risk of respiratory infections

COPD: Chronic obstructive pulmonary disease; DM: Diabetes mellitus; HT: Hypertension.