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BCG skin reaction in Mantoux-negative healthy children
Mohit Singla1, Vaibhav Sahai, Sukhbir Sodhi
1Section of Immunobiology, Yale University School of Medicine, 300 Cedar Street, TAC S 630, New Haven, CT 06510, USA. mohitsingla@gmx.net
Insights
Previously vaccinated children show exaggerated BCG Test responses compared to unvaccinated children. This suggests prior BCG vaccination influences test results, impacting tuberculosis diagnosis in children.
Area of Science:
- Pediatrics
- Immunology
- Infectious Diseases
Background:
- Tuberculosis (TB) presents a significant global health challenge, particularly in pediatric populations.
- Interpreting the Bacillus Calmette-Guérin (BCG) test for TB diagnosis requires careful consideration of prior vaccination status.
- This study investigates BCG reaction patterns in children with and without prior BCG vaccination.
Purpose of the Study:
- To determine the pattern of BCG reaction in children aged 4-6 years.
- To compare BCG test responses between children previously vaccinated with BCG and those not vaccinated.
- To assess the influence of prior BCG vaccination on BCG test interpretation for TB diagnosis.
Main Methods:
- The study included healthy school children aged 4-6 years.
- BCG skin reactions were compared between Mantoux-negative children with and without a previous BCG scar.
- Analysis of variance was performed post-Mantoux and BCG testing.
Main Results:
- Children with prior BCG vaccination (n=50) exhibited a significantly higher rate of exaggerated BCG test responses (78%) compared to unvaccinated children (n=50, 18%) (p < 0.00001).
- The average induration in BCG-immunized children was notably greater than in non-immunized children.
- Exaggerated BCG responses were observed in 80% of males and 76% of females in the previously vaccinated group, versus 16% of males and 20% of females in the unvaccinated group.
Conclusions:
- Prior BCG vaccination can lead to a mild exaggerated BCG Test response (induration up to 8 mm) in healthy children.
- The BCG Test alone should not be the sole criterion for initiating TB chemotherapy in children due to potential drug morbidities.
- An induration up to 8 mm post-BCG Test may be considered normal in Indian settings, potentially due to environmental Mycobacterium exposure or BCG vaccination.
Background:
Tuberculosis poses a great challenge, especially in children. The response of BCG Test may be different in previously vaccinated children and needs to be considered before interpreting positivity for TB. This study has been carried out to determine the pattern of BCG reaction comparing previously vaccinated with non-vaccinated children.
Methods:
The study was conducted in the healthy school children aged 4-6 years. The BCG skin reaction in Mantoux-negative children was compared between children with and without previous BCG scar. After the Mantoux and BCG Test, the analysis of variance was done as per protocol.
Results:
Out of 50 children previously BCG vaccinated, 39(78%) showed exaggerated BCG test responses while out of another 50 children who were not vaccinated for TB, only 9(18%) showed exaggerated BCG Test response (p-value < 0.00001). Average induration obtained in children who were immunized with BCG at birth was much greater than those who were not immunized. 80% and 76% males and females respectively in Group I showed exaggerated BCG response while 16% and 20% males and females respectively of Group II showed exaggerated BCG response.
Conclusion:
The present study indicates that normal healthy children may have a mild exaggerated BCG Test response i.e. induration up to 8 mm because of prior BCG vaccination. Therefore, BCG Test, though important should not be the only criteria for start of chemotherapy for TB in children as the side effects of drugs may cause much morbidity. An induration up to 8 mm after the BCG Test can be normal in Indian settings due to exposure to Mycobacterium in environment and/or BCG vaccine.
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