Objectives: The aims of the present study were to determine the prevalence of LTBI in immigrant children and adolescents (0-17 years) living in or recently coming to Sweden and to estimate the effectiveness of BCG against latent TB (LTBI) in immigrant children coming to Sweden from high-incidence countries, most of them asylum seekers. LTBI was defined as positive Quantiferon or in small children from whom it was difficult to get 3 mL of blood as a tuberculin skin test (TST) of ≥ 10 mm.
Design: As a substitute for written documentation of BCG vaccination a typical BCG scar was used. The study comprised 1,404 immigrants aged 0-17 years. The arms and legs of all of them were inspected for a BCG scar and Quantiferon or TST was performed. The study was a retrospective, observational, comparative cohort study.
Results: Apart from the 1,532 patient records which were reviewed another 301 immigrants were offered a health examination during the same time period but they did not come to the out-patient clinic, despite a reminder, so 16 % of all immigrant children were never tested for LTBI. LTBI was found in 123 of 1011 (12%) children with a BCG scar and in 116 of 393 (29.5 %) without a BCG scar giving an estimated vaccine effectiveness of 59 %.
Conclusions: LTBI is common among immigrant children (17 %). LTBI can progress to active TB and will then spread in the immigrant population and to the general population if all arrivals are not tested and given prophylactic treatment if they have LTBI. The BCG vaccine has a significant effect on LTBI (59 %).


BT graduated as an MD in 1974 at the University of Gothenburg, Sweden. During the first 10 years he worked as an infectious Disease specialist, participated in a diploma course in Tropical Medicine and Parasitology at the Brnhard-Nocht Institute, Hamburg Germany and worked for 2 years at the National Institutes of Health, Bethesda, MD, USA. After that he led a double-blind placebo-controlled tral of an acellular pertussis vaccine. Thereafter he educated himself to be a specialist in Pediatrics and worked through the rest of his professional life as a pediatrician at Sahlgrenska University Hospital, Gothenburg, Sweden (both with pediatrics ibfectious diseases and a general pediatrician): He has published > 200 scientific articles in peer-reviewed international journals, mainly about Haemophilus influenzae type b, invasive pneumococcal infetions, invasive infections in neonates, neuroborreliosis and tuberculosis. He has after his retirement continued to work half-time as a pediatrician.