No Ill Effects When Kids Get Vaccines on Time

Study: On-Time Vaccination Doesn't Have Negative Impact on Development

From the WebMD Archives

May 24, 2010 -- Children should be vaccinated on time because this results in better outcomes than delaying immunization, a study shows.

The research also shows that children who are vaccinated on time have no adverse effects on neuropsychological evaluation seven to 10 years later.

The study is published in the June issue of Pediatrics.

Researchers analyzed data on 1,047 children born between 1993 and 1997, examining their vaccination schedules up to age 1. Then they studied what happened to the kids seven to 10 years later on 42 different neuropsychological tests.

Timely vaccinations were associated with better performance on numerous test outcomes.

And significantly, there was no benefit detected for the kids who had delays in their vaccination schedule or did not receive vaccinations, the researchers say.

Parents who are worried that their kids receive too many vaccines too soon should be comforted by the new data, which shows, like other studies, that vaccination during infancy is safe.

So what are the neuropsychological outcomes studied?

They include speech, language, verbal memory, achievement, fine motor coordination, attention and executive functioning, behavior regulation, tics, and general intellectual functioning.

Vaccine Schedules for Kids

Researchers looked at data on 1,047 kids, 47% of whom, or 491, met the researchers' definition for timely receipt of vaccinations.

The study shows that 235 (23%) of the kids received all recommended vaccines, but not on the recommended time schedule.

And 311 (20%) of the children did not receive all recommended vaccines during the study period.

The researchers found that:

  • 83% of kids had timely vaccines for hepatitis B and 79% for polio. Those were the highest rates.
  • Lowest rates were for DTP (diphtheria, tetanus, pertussis) received on schedule in 65% of the kids.
  • Only 53% received timely immunizations for Hib (Haemophilius influenzae type B).
  • Nine kids did not receive vaccines of any kind during the study period.
  • Children getting vaccines later than doctors' schedules were more likely to be from families with lower household incomes and had a lower percentage of mothers with college degrees.

The researchers write that receipt of all recommended vaccines on time had no negative impact on neuropsychological outcomes by the time the kids had reached 7 to 10 years of age.


"The lack of any statistically significant results that favored delayed receipt of vaccines in the first year of life sends a clear public health message that should be comforting to many parents with vaccine safety concerns," the researchers write. "Children can receive their immunizations on time and expect to have the same neurodevelopmental outcomes as children with any other pattern of vaccine receipt."

This is why vaccines are important and should be administered early, to avoid "negative consequences," the researchers write. "This is particularly true for pertussis, because disease incidence and mortality are highest in children who are younger than six months."

The researchers say the study "provides the strongest clinical outcomes evidence to date that on-time receipt of vaccines during infancy has no adverse effect on neurodevelopmental outcomes seven to 10 years later.

"These results offer reassuring information that physicians and public health officials may use to communicate with parents who are concerned that children receive too many vaccines too soon."

WebMD Health News Reviewed by Laura J. Martin, MD on May 24, 2010



News release, American Academy of Pediatrics.

Smith, M. Pediatrics, June 2010; vol 125.

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