Journal Article 1 Mention
On-time Vaccine Receipt in the First Year Does Not Adversely Affect Neuropsychological Outcomes
Michael J. Smith2010
Charles R. Woods
Top 25% · 75th percentile
33 citations · Health

TLDR

Getting all the recommended vaccines on time in a baby's first year does not harm their thinking or learning abilities when they are older.

Summary

1 Study Aim

The study set out to find out if children who received all their recommended vaccines on schedule during their first year of life had different thinking and learning abilities (neuropsychological outcomes) at ages 7 to 10 compared to children who got their vaccines late or not at all. The study wanted to see if getting vaccines on time in the first year affects how well kids think and learn later.

2 Study Design

The researchers used existing data from a previous Vaccine Safety Datalink study, which included information on when children received their vaccines and results from 42 different tests of thinking and learning skills. They defined 'on-time' vaccination as getting each vaccine within 30 days of the recommended age. The team compared children who got vaccines on time to those who got them late or not at all, using both simple comparisons and more complex statistical models that adjusted for other factors that could affect the results. They also did extra analyses on groups of children who had the most and least vaccines in their first 7 months. The study compared kids who got vaccines on time to those who didn't, using detailed test results and careful statistical checks.

3 Findings

The study found that children who received their vaccines on time sometimes did better on certain thinking and learning tests, but these differences mostly disappeared after adjusting for other factors. There were no cases where children who got vaccines late or not at all did better than those who got them on time. In additional analyses, children who had the most vaccines early in life did not show worse outcomes than those who had fewer vaccines. The authors conclude that getting vaccines on time in infancy does not harm children's thinking or learning abilities years later. They suggest these results should reassure parents who worry about too many vaccines too soon. The results show that getting vaccines on time as a baby does not hurt how well kids think or learn when they are older.

Abstract

OBJECTIVES: To determine whether children who received recommended vaccines on time during the first year of life had different neuropsychological outcomes at 7 to 10 years of age as compared with children with delayed receipt or nonreceipt of these vaccines. METHODS: Publicly available data, including age at vaccination, from a previous VaccineSafety Datalink study of thimerosal exposure and 42 neuropsychological outcomes were analyzed. Vaccine receipt was defined as timely when each vaccine was received within 30 days of the recommended age. Associations between timeliness and each outcome were tested in univariate analyses. Multivariable regression models were constructed for further assessment of the impact of timeliness on neuropsychological outcomes after adjustment for potential confounders. Secondary analyses were performed on a subset of children with the highest and lowest vaccine exposures during the first 7 months of life. RESULTS: Timely vaccination was associated with better performance on 12 outcomes in univariate testing and remained associated with better performance for 2 outcomes in multivariable analyses. No statistically significant differences favored delayed receipt. In secondary analyses, children with the greatest vaccine exposure during the first 7 months of life performed better than children with the least vaccine exposure on 15 outcomes in univariate testing; these differences did not persist in multivariable analyses. No statistically significant differences favored the less vaccinated children. CONCLUSIONS: Timely vaccination during infancy has no adverse effect on neuropsychological outcomes 7 to 10 years later. These data may reassure parents who are concerned that children receive too many vaccines too soon.

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