Scar Formation and Tuberculin Skin Test Response After Bacillus Calmette-Guerin Vaccination: Does Prematurity or Low Birth Weight Have an Impact?

Objectives: The present study aimed at evaluating factors affecting scar formation and tuberculin skin test (TST) response in Bacillus Calmette-Guerin (BCG) vaccinated infants.
Methods: In the current study, 216 infants with gestational age (GA) of 26 to 40 weeks and birth weight of 730 g to 4590 g were included. The mean corrected age was 6.27 ± 3.79 weeks, and the mean weight was 4442.4 ± 1084.1 g (range 2100 - 7700 g) at the time of BCG vaccination. TST was applied at 8 to 16 weeks of vaccination. Factors affecting TST response and BCG scar formation were evaluated.
Results: A scar response to BCG vaccination was found in 60%, 49.4%, and 59.7% of the infants with GA < 32 weeks, 33 to 36 weeks, and ≥ 37 weeks, respectively. Of the male infants 65% produced a scar compared to the 45% of the female infants (P = 0.014). The mean weight at the time of vaccination was significantly higher in infants with scar development than in those without scars (6976.94 g vs. 6455.68, P = 0.002). A tuberculin reaction was detected in 57% of the infants (80%, 54%, and 50% according to birth weight > 2500 g, 1500 - 2500 g, and < 1500 g, respectively) (P = 0.213). TST response rate was 67%, 55%, and 47% according to GA ≥ 37 w, 33 - 36 w, and ≤ 32 w, respectively (P = 0,020). In the present study, 68.4% of the cases with TST of 5 - 10 mm, and 100% of the cases with TST > 10 mm developed scars ≥ 2mm (r = 0.360; P = 0.001).
Conclusions: Prematurity or birth weight does not affect BCG scar formation. TST response is lower in preterm babies. The correlation between scar formation and TST response was too low to be interpreted as positive.

Keywords
Infant; Premature; Small for Gestational Age; BCG Vaccine; Vaccination; Tuberculin Test