Abstract

Background 25-OH vitamin D levels above 30 ng/mL activate HCAP-18, which impacts the immune response to respiratory viruses. While emerging data suggests a link between low levels of 25-OH vitamin D and an increased incidence of respiratory infections, the relationship between these levels and severity of infection is unknown. We hypothesized that infants with insufficient 25-OH vitamin D levels would have more severe viral respiratory infections. Methods Healthy infants admitted with fever and cough or congestion were prospectively enrolled and 25-OH vitamin D levels were measured. Presumptive bacterial infections were excluded. Nasopharyngeal specimens were collected for determination of viral etiology by polymerase chain reaction (PCR). Demographics and severity markers were recorded. Levels were categorized as sufficient (≥ 30 ng/mL), or insufficient (< 30 ng/mL). Results We enrolled 90 subjects. 25-OH vitamin D was < 30 ng/mL in 66%. Respiratory syncytial virus (RSV) was the most common virus. On multivariable analysis, breastfeeding was the only risk factor found to be associated with insufficiency. Administration of antibiotics and intravenous fluid, and PICU admission were not significantly different in infants with insufficient levels. However, infants with insufficient vitamin D had increased durations of both hospitalization (1.4 days, 95% confidence interval (CI) = 1.0-1.9 days) and oxygen use (2.2 days, 95% CI = 1.4-3.5 days), and used a higher level of oxygen supplementation (odds ratio = 4.58, 95% CI = 1.58-13.23). Conclusions Infants with 25-OH vitamin D insufficiency had more severe viral respiratory illnesses. Breastfeeding was associated with insufficiency. Vitamin D supplementation during pregnancy might be a strategy to reduce risk and severity of respiratory illness in infants.

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