Inclusion Criteria:  The study population consists of children in the age group 1-5 years admitted to a pediatric ward, due to an acute episode with asthma-like symptoms. An acute asthma-like episode will be defined as annoying coughing, wheezing (wheezing or wheezing in connection with exhalation) and / or dyspnoea, which affects the child's well-being and requires hospitalization in a pediatric ward. Participation in the study requires that the child is in or has been in treatment with SABA, as monotherapy, or in combination with ICS, and possibly also in combination with LTRA in accordance with the Danish guidelines  Exclusion Criteria:  The child is hospitalized with pneumonia The child's daily intake of vitamin D supplementation is> 400 IU / day (~ 10 μg / day). The child is given a combination of vitamin and dietary supplements containing vitamin D, thus the daily recommended dose is exceeded, as 2400 IU / day (~ 60 μg / day) is accepted for children aged 1-4 years, as everyone here is recommended to take 400 IU / day (~ 10 μg / day) by the Danish Health and Medicines Authority. The baby has been exclusively breastfed for the past 6 months.  The child is malnourished  for children> 2 years of age whose age-specific BMI is less than the 3rd percentile. for children <2 years, whose weight or height in relation to age is less than the 3rd percentile. The child is a newly arrived refugee or immigrant from regions with a high risk of rickets. The child has other chronic lung diseases. The child is diagnosed with other conditions such as chronic lung disease, impaired renal function, neurological or psychiatric disorders, congenital or documented acquired QT prolongation, clinically relevant bradycardia, cardiac arrhythmia or severe heart failure and / or hepatic impairment. The child is being treated with medication that alters calcium or vitamin D absorption / metabolism.