Estimating Tuberculin Skin Test Reactions among Children and Teenagers Who Received the Bacillus Calmette-Guerin Vaccination at Birth: A Meta-analysis

OBJECTIVES Tuberculin skin reaction size is one indicator of bacillus Calmette-Guérin (BCG) vaccine efficacy and a way to diagnose latent infection. Several primary studies have examined this issue. Combining the results of these studies using a meta-analysis will provide reliable evidence regarding this indicator for policymakers. This study aimed to estimate the total frequency of different tuberculin skin test reactions among Iranian children and teenagers who received the BCG vaccination at birth. METHODS National and international databanks were searched using relevant keywords. After the search strategy was restricted and duplicates were excluded, the titles and abstracts of the remaining papers were screened. All included studies included healthy children who received the BCG vaccine without confirmed tuberculosis exposure. Heterogeneity of the results was assessed using the Cochrane test and I2 index showed the random effects model as the best model for estimating the pooled results. RESULTS We combined the results of 14 primary studies including purified protein derivative reaction test measures of 26,281 Iranian children. The frequencies (95% confidence intervals) of the reactions were 8.5% (6.2-10.8) for patients with a reaction size ≥ 10 mm, 29.9% (22.3-37.4) for a reaction size of 5-9 mm, and 60% (48.9-71.1) for a reaction size < 5 mm. CONCLUSION Our study showed that large numbers of Iranian children and teens have no positive BCG vaccine reaction and a considerable number of children have been exposed to Mycobacterium tuberculosis.