Time of perinatal immunization, thimerosal exposure and neurodevelopment at 6 months in breastfed infants

• Published in: Acta Paediatrica 2007-06, Vol.96 (6), p.864-868
• Main Authors: Marques, Rejane C, Dórea, José G, Manzatto, Angelo G, Bastos, Wanderley R, Bernardi, José VE, Malm, Olaf
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Body Weight; Brazil; Breast Feeding; Breastfeeding; Developmental Disabilities - chemically induced; Ethylmercury; Ethylmercury Compounds - administration & dosage; Ethylmercury Compounds - adverse effects; Female; General aspects; Hepatitis B Vaccines - administration & dosage; Hepatitis B Vaccines - chemistry; Humans; Immunization Schedule; Infant, Newborn; Male; Maximum Tolerated Dose; Medical sciences; Neurodevelopment; Neuropsychological Tests; Preservatives, Pharmaceutical - administration & dosage; Preservatives, Pharmaceutical - adverse effects; Prevention and actions; Public health. Hygiene; Public health. Hygiene-occupational medicine; Thimerosal; Thimerosal - administration & dosage; Thimerosal - adverse effects; Time Factors; Vaccines
• ISSN: 0803-5253; 1651-2227
• DOI: 10.1111/j.1651-2227.2007.00288.x

Aim: Brazilian newborns immunized with hepatitis‐B (thimerosal containing vaccine, TCV) receive the first dose within 24 h if delivered in public hospitals, but at a later time if born in private hospitals. We compared neurodevelopment (ND) in infants born in a state hospital (immunized within 24 h) and in privately run hospitals (immunized 2–4 days postnatally). Methods: We used the Gesell Developmental Schedules in 82 healthy exclusively breastfed infants at 6 months to assess motor skills, language development, comprehension capacity and social skills. Results: Compared to the group immunized 2–4 days after hospital discharge, the group immunized within 24 h showed no significant difference in ND delays. Despite the variation in gestational age (range 36–42 weeks) and TCV‐ethylmercury (EtHg) dose (5.7–11.3 μgHg/kg b.w.) at birth, time of exposure to TCV showed no significant association with ND. Gesell Developmental Score was not significantly correlated with total parenteral EtHg/unit of body mass neither with the relative increase in hair‐Hg (as an additional challenge to prenatal Hg exposure). Conclusion: In breastfed infants, differences in early exposure to TCV‐EtHg cannot portend clinical neurodevelopment delays at 6 months. We speculate that breastfeeding remains a significant strategy to improve central nervous system protection of infants facing early exposure challenges.