Please select the eligibility criteria that correspond to the clinical trial below.
Title: Vitamin D vs. Placebo in the Prevention of Viral-induced Exacerbations in Preschoolers With Asthma: a Pilot RCT
Brief Summary: Viral infections are the main cause of asthma attacks in preschoolers, an age group with the highest rate of emergency visits due to asthma. While high doses of inhaled or oral corticosteroids provide benefits, these have been associated with adverse outcomes. Most asthmatic children have lower blood levels of vitamin D compared to non-asthmatic children. Low vitamin D level has been linked to more frequent and more severe asthma attacks as well as with higher dose requirement of inhaled corticosteroid. Recent studies show that vitamin D supplements can reduce the number of asthma attacks triggered by viral infections in children. Unfortunately, most people forget to take vitamin D every day during the fall and winter season as recommended in Canada. A solution is to give a vitamin D bolus by mouth. This has been shown to safely and effectively increase vitamin D levels in children. The investigators hypothesise that a vitamin D bolus given in clinic will sufficiently increase the blood level of vitamin D to prevent the expected winter decline in vitamin D, compared with placebo in preschool-aged children with asthma. This six-month pilot randomized controlled trial aims to: (1) show that a vitamin D bolus is superior to placebo in raising vitamin D levels; (2) record the number of asthma attacks and viral infections in enrolled participants; and (3) identify problems that may call for protocol changes.


Options:
A: Inclusion Criteria:

* Preterm infants born between 24 and 32 weeks of gestation (estimated by ultrasound)
* In born or admitted to the unit within 48hours from birth.
* Randomization within 7 days from birth.
* Parental consent.
* Mothers willing to return for follow up visits.

Exclusion Criteria:

* Preterm delivery \>=33 weeks of gestation or term delivery (estimated by ultrasound).
* Major congenital abnormalities.
* Participation in another trial.
* Severe illness at birth deemed incompatible with survival.
* Congenital HIV infection.
* Total parenteral nutrition \> 14 days.
* Cholestasis
B: Inclusion Criteria:

* Healthy mothers \> 18 years of age
* Term, healthy infants eligible to receive the Bacille-Calmette- Guerin (BCG) vaccine

Exclusion Criteria:

* Recent maternal history of tuberculosis (within 1 year) or active tuberculosis
* Known maternal human immuno-deficiency virus (HIV) infection
* Maternal fever or chorio-amnionitis
* Maternal use of vitamin D, steroids or immuno-regulatory medications
* Household member with active tuberculosis
C: Inclusion Criteria:

* children aged 1-5 years
* physician-diagnosed asthma as per GINA guidelines
* upper respiratory tract infections as the main asthma exacerbation trigger
* ≥4 respiratory infections in the past 12 months
* ≥1 exacerbation requiring rescue oral steroids in the past 6 months or ≥2 in the previous 12 months.

Exclusion Criteria:

* extreme prematurity (\<28 weeks gestation)
* infants \<12 months of age
* breastfed infants with no vitamin D supplementation
* recent (\<1 year) immigrants from countries where rickets and malnutrition prevalent
* other chronic respiratory disease (broncho-pulmonary dysplasia; cystic fibrosis)
* endocrine disorder of calcium/ vitamin D metabolism
* disorder/ disease with associated malabsorption (inflammatory bowel disease)
* kidney/ liver disease
* sickle cell anemia
* medications known to interfere with bone metabolism/ vitamin D levels
* vitamin D supplementation \>1000 IU/ day in past 3 months
* unable to attend medical visit in 3-4 months
* plan to leave the province during the next 6 months.
D: Inclusion Criteria:

* Clinical features of rickets
* Active rickets on X-ray

Exclusion Criteria:

* Treatment with calcium or vitamin D in preceding 30 days

Answer: C