Studies from low-income countries report positive non-specific effects of early Bacillus Calmette-Guérin (BCG) immunisation on childhood health and survival. Neonatal immunisation with BCG may prime the immune system and offer partial protection against other infectious and possibly allergic diseases. The potential clinical value of these non-specific effects has not yet been examined in a large randomised trial in high-income countries. The Danish Calmette Study is a multicentre randomised clinical trial conducted between October 2012 and November 2015. Within the first 7 days of life, infants were randomly assigned to intra-dermal vaccination with BCG or no intervention. At 3 and 13 months of age structured telephone interviews and clinical examinations of the children were conducted. In a subgroup of children blood samples were drawn and stool samples collected at age 4 days, 3 and 13 months. Thymus index was assessed by ultrasound in a subgroup at randomisation and at 3 months. The primary study outcome is hospitalisation within the first 15 months of life as assessed in Danish health registers. Secondary outcomes include infectious disease hospitalisations, wheezing, eczema, use of prescribed medication, growth, development, thymus index, T- and B-cell subpopulations assessed by flow cytometry, in vitro cytokine responses and specific antibody responses to other vaccines. Adverse reactions were registered. With participation of 4184 families and more than 93% adherence to clinical follow-up at 3 and 13 months, this randomised clinical trial has the potential to create evidence regarding non-specific effects of BCG vaccination in a high-income setting.

Obesity amongst children is a growing problem worldwide. In contrast to adults, little is known on the effects of controlled weight loss on components of the metabolic syndrome in children. The primary aim of the study was to evaluate the effects of a 20-week exercise and diet guidance intervention on body mass index (BMI) in a group of overweight children. Our hypothesis was an observed reduction in BMI and secondarily in body fat content, insulin insensitivity, and other components of the metabolic syndrome in the intervention group.

BCG vaccination has been associated with beneficial non-specific effects on child health. Some immunological studies have reported heterologous effects of vaccines on antibody responses to heterologous vaccines. Within a randomised clinical trial of Bacille Calmette-Guérin (BCG) vaccination at birth, The Danish Calmette Study, we investigated the effect of BCG at birth on the antibody response to the three routine vaccines against DiTeKiPol/Act-Hib and Prevenar 13 in a subgroup of participants. Within 7days after birth, children were randomised 1:1 to BCG vaccination or to the control group (no intervention). After three routine vaccinations given at age 3, 5 and 12months, antibodies against DiTeKiPol/Act-Hib and Prevenar 13 (Streptococcus pneumoniae serotype type 4, 6B, 9V, 14, 18C, 19F and 23F) were measured 4weeks after the third vaccine dose. Among the 300 included children (178 BCG; 122 controls), almost all children (>96%) had antibody responses above the protective levels. Overall BCG vaccination at birth did not affect the antibody level. When stratifying by 'age at randomisation' we found a possible inducing effect of BCG on antibodies against B. pertussis and all pneumococcal serotypes, when BCG was given after the first day of life. Girls had significantly higher antibody levels for Haemophilus influenza type b and pneumococcus than boys. Three routine vaccinations with DiTeKiPol/Act-Hib and Prevenar 13 induced sero-protective levels in almost all children. No overall effect of neonatal BCG vaccination was observed.

To evaluate adverse reactions of the Bacillus Calmette-Guérin (BCG) Statens Serum Institut (SSI) (Danish strain 1331) used as intervention in a randomized clinical trial. A randomized clinical multicenter trial, The Danish Calmette Study, randomizing newborns to BCG or no intervention. Follow-up until 13 months of age. Pediatric and maternity wards at three Danish university hospitals. All women planning to give birth at the three study sites (n=16,521) during the recruitment period were invited to participate in the study. Four thousand one hundred and eighty four families consented to participate and 4262 children, gestational age 32 weeks and above, were randomized: 2129 to BCG vaccine and 2133 to no vaccine. None of the participants withdrew because of adverse reactions. Trial-registered adverse reactions after BCG vaccination at birth. Follow-up at 3 and 13 months by telephone interviews and clinical examinations. Among the 2118 BCG-vaccinated children we registered no cases of severe unexpected adverse reaction related to BCG vaccination and no cases of disseminated BCG disease. Two cases of regional lymphadenitis were hospitalized and thus classified as serious adverse reactions related to BCG. The most severe adverse reactions were 10 cases of suppurative lymphadenitis. This was nearly a fivefold increase compared to what was expected based on the summary of product characteristics of the vaccine. All cases were treated conservatively and recovered. Six of 10 (60%) families of children experiencing suppurative lymphadenitis compared to 117/2071 (6%) of those with no lymphadenitis indicated that the vaccine had more adverse effects than expected (p-value <0.001). BCG vaccination was associated with only mild morbidity and no mortality. A higher incidence of suppurative lymphadenitis than expected was observed. All children were treated conservatively without sequelae or complications. Trial registration number NCT01694108 at www.clinicaltrials.gov.

The Bacillus Calmette–Guérin vaccine (BCG) has been associated with beneficial non-specific effects (NSEs) on infant health. Within a randomized trial on the effect of neonatal BCG on overall health, we investigated the possible immunological impact of neonatal BCG vaccination on lymphocyte subsets, determined by flow cytometry. In 118 infants blood samples were obtained 4 (±2) days post randomization to BCG vaccination or no intervention, and at 3 and 13 months of age. No effects of BCG were found at 4 days. However, BCG increased proportions of effector memory cells at 3 months (Geometric mean ratio (GMR) 1.62, 95% confidence interval (CI) (1.20–2.21), p = 0.002 for CD4⁺ T cells and GMR 1.69, 95% CI (1.06–2.70), p = 0.03 for CD8⁺ T cells), and reduced proportions of late differentiated CD4⁺ T cells (GMR = 0.62, 95% CI (0.38–1.00), p = 0.05) and apoptotic CD4⁺ T cells at 13 months (GMR = 0.55, 95% CI (0.32–0.92), p = 0.03). In conclusion, limited overall impact of neonatal BCG vaccination on lymphocyte subsets was found in healthy Danish infants within the first 13 months of life. This is in line with the limited clinical effects of BCG observed in our setting.

The Bacillus Calmette-Guérin vaccine (BCG) against tuberculosis is administered intradermally, and vaccination is often followed by a scar at the injection site. Among BCG-vaccinated individuals, having a scar has been associated with lower mortality. We aimed to examine the impact of vaccination technique for scarring in a high income setting, by assessing the associations between the post injection reaction, the wheal size, and the probability of developing a scar, and scar size. This study was nested within a clinical multicenter study randomizing 4262 infants to either BCG vaccination (BCG 1331 SSI) or no intervention. In this substudy, including 492 vaccinated infants, the immediate post BCG vaccination reaction was registered as either wheal (a raised, blanched papule at the injection site), bulge (a palpable element at the injection site), or no reaction. The presence or absence of a BCG scar and the size the scar was measured at 13 months of age. Of 492 infants included, 87% had a wheal after vaccination, 11% had a bulge, and 2% had no reaction. The mean wheal size was 3.8 mm (95% confidence interval 3.7–3.9). Overall, 95% (442/466, 26 lost to follow-up) of BCG-vaccinated infants had a scar at 13 months of age. In infants with a wheal, the probability of developing a scar was 96%, declining to 87% in the case of a bulge, and to 56% in the case of no reaction (p for same probability = 0.03). Wheal size was positively correlated with the probability of getting a scar and scar size. Scarring after BCG vaccination has been associated with lower infant mortality. In a high-income setting, we found that correct injection technique is highly important for the development of a BCG scar and that registration of the category of BCG skin reaction (as wheal, bulge, or no reaction) may be used to identify infants at risk of scar failure. Finally, the wheal size was positively associated with both the probability of getting a scar and scar size. The study was registered at www.ClinicalTrials.gov with trial registration number NCT01694108 .