BCG vaccination and immune response in preterm infants: The role of gestational age

Aim: To evaluate and correlate the immune response of premature infants after BCG vaccination Methods: Three groups of infants received BCG vaccination; preterm at birth, preterm when they reached chronological term, and term infants. All were evaluated for BCG scar, PPD induration and lymphocyte proliferation test (LTT) Results: Out of 254 vaccinated infants of different gestational ages, 113 returned for PPD and LTT, and of those, 98 returned for PPD reading. Fifty-two preterm infants were vaccinated at birth, 29 were vaccinated when they reached at term, and 31 full-term vaccinated at birth: (a) There was a correlation between the BCG scar and both PPD>5mm indurations and LTT>=2 response. In contrast, no correlation was found between PPD indurations and LTT, (b) Birth weight and gestational age were significantly correlated with LTT response but neither correlated with BCG scar or PPD induration, (c) There was significant increase in response in (LTT) when preterms were vaccinated at =>34 weeks gestational age (P=0.001) but this was not significantly correlated with PPD induration or positive BCG scar. Conclusions: Our study indicates that delaying BCG vaccination in very low birth weight preterm infants until they reach 34 weeks gestational age may providesomewhat better protection. There was no correlation between PPD induration and LTT response. These two tests may measure two different dimensions of immune response. Additional longitudinal studies are needed to follow-up preterms after BCG vaccination to measure the duration of their immunity and indicate an age for revaccination.