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What is the significance of an accelerated BCG reaction in children?
  1. Paola Villanueva1,2,
  2. Laure F Pittet1,3,
  3. Clare Nourse4,5,
  4. Nigel Curtis1,2
  1. 1 Department of Paediatrics, The University of Melbourne, Parkville, Victoria, Australia
  2. 2 Infectious Diseases Unit, The Royal Children's Hospital Melbourne, Parkville, Victoria, Australia
  3. 3 Infection and Immunity, Murdoch Children's Research Institute, Parkville, Victoria, Australia
  4. 4 Infection Management and Prevention Service, Queensland Children’s Hospital UQ Faculty, South Brisbane, Queensland, Australia
  5. 5 Faculty of Medicine, The University of Queensland, Herston, Queensland, Australia
  1. Correspondence to Professor Nigel Curtis, Department of Paediatrics, The University of Melbourne, Parkville, VIC 3052, Australia; nigel.curtis{at}

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Clinical scenario

You are asked to review a 7-month-old infant born in Australia who was given BCG the previous day in preparation for travel to India. Her parents have noticed a 6 mm diameter swelling at the injection site. You are aware that an accelerated response at a BCG injection site may be associated with underlying tuberculosis (TB) infection. The infant is otherwise completely well with a normal examination. You wonder whether you should investigate further.

Structured clinical question

Is an accelerated local reaction following BCG vaccination in a child indicative of underlying TB (latent TB infection (LTBI) or active TB disease)?

Search strategy and outcome

Medline (1946 to current), PubMed and Embase databases were searched in September 2021 with the search terms detailed in the online supplemental search strategy. Our systematic search identified 139 articles. Of these, 14 fulfilled the inclusion criteria of English-language publications addressing accelerated local reaction to intradermal BCG for diagnosing TB in children under 18 years of age. All the studies reported sensitivity but only seven included controls enabling specificity to be calculated.

Supplemental material



BCG is one of the most extensively used vaccines worldwide, given to children to protect against TB since 1921. It has received more recent attention for its beneficial off-target effects on the immune system, associated with protection against other diseases.1 The normal reaction to intradermal BCG vaccination is the appearance of a small, red papule or swelling at the injection site within 2–3 weeks. Usually, the papule softens, resulting in a small ulcer, healing over several weeks to months into a small flat scar.2 3 In some individuals, an ‘accelerated local reaction’ occurs, commonly defined as the early development of an induration or swelling of 5 mm or more at the injection site, beginning within 24–72 hours of vaccination.4–6 An accelerated BCG reaction has also been called a ‘positive BCG …

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  • Contributors PV drafted the initial manuscript. LFP, CN and NC critically revised the manuscript and all authors approved the final version as submitted.

  • Funding PV is supported by the Australian Government Research Training Programme Scholarship provided by the Australian Commonwealth Government and the University of Melbourne, and a Murdoch Children's Research Institute (MCRI) PhD Top-Up Scholarship.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; internally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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