People at risk

With some exceptions, it is young children under the age of two who are most at risk. Among these, some are nevertheless more susceptible to the disease:

• premature babies;
• infants less than six weeks old;
• children with a family history of bronchial asthma;
• those with congenital heart disease;
• those whose lungs have developed abnormally (bronchodysplasia);
• those who suffer from cystic fibrosis of the pancreas (or cystic fibrosis), a genetic disease. This disease causes excessive viscosity of the secretions of the glands in various places of the body, including the bronchi.
• Native American and Alaskan children.

Risk factors

• Being exposed to secondhand smoke (especially when it comes to the mother).
• Go to daycare.
• Living in a disadvantaged environment.
• Live in a large family.
• Vitamin D deficiency at birth. A study⁵ reported that a low concentration of vitamin D in the umbilical cord blood is associated with a six times higher risk of possible bronchiolitis.