Early exposure to thimerosal-containing vaccines and children's cognitive development : a 9-year prospective birth cohort study in Poland

The controversial topic of the early exposure to mercury is regarding ethylmercury, which is present in the thimerosal-containing vaccines (TCVs). The objective of this study was to determine the relationship between the early exposure to TCVs and cognitive development in children during the first 9 years of life. The cohort included 318 children vaccinated in an early period (neonatal and up to 6 months) against hepatitis B and diphtheria-tetanus-pertussis (DTP) using formulation with or without thimerosal. The children’s development was assessed using the Fagan test (6th month of life), the Bayley Scales of Infant Development (BSID)-II (12th–36th month), the Raven test (5th, 8th year), and the Wechsler Intelligence Scale for Children (WISC-R) (6th, 7th, 9th year). Results were determined by multivariable linear and logistic regression, adjusted to potential confounders. Children exposed and not exposed to TCVs in the neonatal period had similar outcomes of cognitive-developmental tests; only the results of BSID-II at the 36th month and WISC-R at the 9th year were significantly higher for those exposed to TCVs. Developmental test results in children exposed to TCVs up to the 6th month of life also did not depend on thimerosal dose. Conclusion: TCV administration in early infancy did not affect children’s cognitive development

The effectiveness of rotavirus vaccine in preventing acute gastroenteritis during rotavirus seasons among Polish children

Introduction: Rotavirus is the main etiological cause of intestinal infections in children. Voluntary rotavirus vaccines were included in the Polish vaccination schedule in 2007. The aim of this study was to assess the effectiveness of a completed rotavirus vaccination course in preventing acute gastroenteritis in Polish infants during their first five years of life. Material and methods: This was a retrospective cohort study conducted in Lesser Poland (Malopolska Province). The sample population included a group of 303 children who received the completed rotavirus vaccination course and 303 children not vaccinated against rotavirus. The date of the child’s acute gastroenteritis diagnosis and his or her vaccination history were extracted from the physicians’ records. Each kind of diagnosed acute gastroenteritis during winter-spring rotavirus seasons was treated as the endpoint. The relative risk of having gastrointestinal infection was assessed using the hazard ratio from the Cox proportional hazards regression model. Results: In the examined group, 96 (15.8%) children had winter-spring gastrointestinal infections. In the non-vaccinated children, the cumulative incidence of these infections in the first 5 years of life was 20.8%, whereas in the children vaccinated with Rotarix it was only 10.9%. Those who were vaccinated with Rotarix had a 44% reduction in the risk of a winter-spring acute gastroenteritis infection compared to those not vaccinated with Rotarix (p = 0.005). Birth weight less than 2500 g increased the risk of the infection twofold and also reached statistical significance (p = 0.044). Conclusions: The results showed that Rotarix is effective in preventing acute gastroenteritis in Polish children during rotavirus seasons

Whole-cell pertussis vaccine (DTwP) has no influence on allergic diseases and atopic sensitization in children

Introduction: Vaccine opponents indicate that the infant's immune system is inadequately developed to handle multiple vaccines which may overwhelm the immune system, leading to allergic diseases. Aim: To verify the association between the vaccine antigen overload derived from DTwP and the development of atopic sensitization and allergic diseases. Material and methods: Data from an earlier established birth cohort in Krakow, followed up to the 6th year of life were used. Allergic diseases such as eczema, hay fever and asthma were diagnosed by a physician and reported every half a year from the 1st to 6th year of life by the child’s parent. Skin prick tests (SPT) were performed in children at 5 years of age. The data on infants' vaccination were extracted from the physician's records. The status of vaccine antigen exposure was based on different types of vaccines against pertussis (DTwP or DTaP) in a primary course. Results were determined by multiple logistic regression, adjusted to potential confounders. Results: The analyzed population consisted of 234 children: 53.4% - boys and 46.6% - girls. Infants up to the age of 8 months were vaccinated with the primary course against pertussis, with DTwP - 60.7%, DTaP - 32.9% and further 6.4% with a mixed course (DTwP + DTaP). There were no significant relationships between any of vaccination groups and allergic disease and allergen sensitivity in the multiple logistic regression model with adjustment to potential confounders. Conclusions: The exposure to a large number of vaccine antigens derived from DTwP has no influence on the development of allergic diseases and atopic sensitization in children