Foreign background and older age of children were associated with infection in Swedish tuberculosis contacts.

Aim: We present our results using interferon-gamma release assays in any child <18 years or tuberculin skin tests in Bacille Calmette-Guérin unvaccinated children for tuberculosis contact investigation in Stockholm, Sweden.

Methods: During 2000-2019, we investigated 892 children with a median age of seven years. We explored associations between TB infection and characteristics such as closeness to contact, age, sex, BCG status and foreign origin.

Results: The overall rates were for TB infection 10.2% (n = 91) and for TB disease 1.1% (n = 10). In addition to infectiousness of index case and closeness of contact, foreign background, male sex and increasing age were independently associated with infection. In foreign-born children, the rates of tuberculosis infection and disease were 18.7% and 3.9%, respectively. In 18/46 (39%) infected foreign-born children, a baseline negative tuberculosis test supported a diagnosis of recent infection.

Conclusion: Foreign background, older age and male sex were associated with infection. In a significant proportion of infected children, a previous negative test made recent infection likely.