A new study aims to put those fears to rest.

According to an article published today in the New England Journal of Medicine, children who receive the whole-cell pertussis (DTP) vaccine, or measles, mumps and rubella (MMR) vaccine, may be at an increased risk of developing rare seizures brought on by a high fever.

However, the numbers are low, 6 to 9 seizures per 100,000 children are attributed to the DTP vaccine, and 25 to 34 per 100,000 children to the MMR vaccine. Both vaccines are given in a series during the infant years, and once more before children start school.

Researchers from University of Washington and the Kaiser Vaccine Study, examined the medical records of nearly 700,000 children. The DTP vaccine was only associated with an increased risk of seizure on the day it was administered. The MMR vaccine was associated with an increased risk of seizures eight-to-14 days after vaccination.

'Scary' Seizures Not Harmful

The researchers are also quick to point out that although the seizures may be "scary" at the time for both children and parents, no long-term neurological damage is done.

"A very important part of this study is the observation that these events, although the seizures did occur, were not associated with any long-term problems in these children," says Dr. Steven Black, co-director of the Kaiser Vaccine Study and co-author of the New England Journal study.

Black also points out that the study examined the effects associated with the DTP vaccine, which has long been the subject of debate.

"In the past, there has been a considerable amount of controversy surrounding the safety and side effects of vaccines, especially the DTP," says Dr. Bob Davis, second author of the study and professor of pediatrics and epidemiology at the University of Washington. DTP is rarely used anymore because it caused fever in a lot more children. (The study began in the early 1990s when it was the primary vaccine give to protect against the disease.)

A similar version, the DtaP, is now a popular alternative among pediatricians. Its side effects are currently being studied.

Advice to Parents

"Parents need to be aware that vaccines can cause fever leading to seizures," says Black. "So, it makes sense for them to look for signs of a fever, and if one develops, give the child Tylenol, because they're less likely to have a problem," he advises. While some researchers have brushed aside the study as nothing new, one anti-vaccine activist disagrees.

"It's a big deal if it's your kid," says Debby Bermudes, executive director of the Massachusetts Citizens for Vaccination Choice. "What we have to remember is that vaccines are a non-emergency medical procedure. And like all procedures, parents should be given full disclosure and decide if they want to take those risks."

Benefits of Vaccines

Dr. Gregory Poland, chief of the Mayo Clinic Vaccine Research Group and American editor of the journal VACCINE, stresses the importance of having children vaccinated, and points out that if they develop the actual disease they are at an even higher risk of having seizures, as well as more serious complications such as brain damage.

So in the end, he says, the benefits of vaccines outweigh the risks.

"We must constantly make the point of the value of these vaccines in preventing the thousands and thousands of deaths and disabilities that would have resulted in the absence of vaccination. Bottom line: these vaccines are safe and effective."