Bacille Calmette Guérin Immunisation at Birth and Childhood Morbidity in Danish Children.

In high-income societies the use of health care and medication is steadily increasing. Children have high morbidity, many visits at the general practitioner, an increasing number of hospitalisations, and an increasing use of medication. And, when children are ill, someone has to stay home to care for them. An un-explained global increase in the incidence of the allergic diseases eczema, wheezing, asthma and allergies means that 25% of high-income populations are affected. Cheap preventive measures are highly warranted. Recent studies have shown a positive, non-specific effect of early Bacille Calmette Guérin (BCG) immunisation on neonatal mortality in low-income countries and suggested a positive, non-specific effect on allergic disease in high-income countries. "Non-specific" means that the vaccine effect goes beyond prevention of the targeted disease, i.e. the BCG vaccine benefits the health status of the immunised individual in ways unrelated to protection against tuberculosis (TB). For instance, in a recent randomised trial in West Africa the investigators showed that the BCG vaccine at birth was safe in low birth weight (LBW) infants and significantly reduced neonatal mortality in these children, with a significant long-lasting effect on infant mortality in the smallest newborns with a birth weight <1.5 kg. There is an urgent need to explore the huge potential of the BCG's beneficial immune-stimulatory effects among children in high-income populations.

Therefore, the investigators will carry out a large prospective randomised clinical trial in Denmark primarily designed to test the hypothesis that infants who get the BCG vaccine at birth experience 20% fewer hospitalisations during early childhood.

Secondary outcomes

1. To test the hypothesis that infants who get the BCG vaccine at birth are prescribed less antibiotics during early childhood than non-BCG-immunised infants.
2. To test the hypothesis that Danish infants who get the BCG vaccine at birth develop less eczema, asthmatic bronchitis/wheeze and food allergy at 3 and 12 months of age: self-reported, diagnosed by a physician, or found at clinical examination; and are prescribed less anti-eczema/asthma/allergy medication during early childhood than non-BCG-immunised infants.
3. To test the hypothesis that infants who receive the BCG at birth respond in paraclinical measures: Specific IgE, thymic gland size, leucocyte count and differentiation, monocyte memory, cytokine profiles, and antibody titres following immunisation against diphtheria, tetanus, pertussis, pneumococcus, hemophilus.
4. To test the hypothesis that infants who get the BCG vaccine at birth respond in growth measures: weight, length and head circumference.
5. To test the hypothesis that infants who get the BCG vaccine at birth respond with decreased morbidity: common cold, pneumonia, febrile episodes, diarrhoea and vomiting, acute otitis media, febrile convulsions.
6. To test the hypothesis that premature infants with gestational age less than 37 weeks who get the BCG vaccine at birth have unaffected psychomotor development measures: Ages and Stages scores.
7. To test the hypothesis that infants who get the BCG vaccine at birth has unaffected coverage with the subsequent vaccinations in the Child Vaccination Programme.
8. To test the above mentioned hypotheses specifically in the strata of premature and low-birth-weight Danish infants.