Kids’ seizure risk from combo vaccine could give anti-vaccinationists fresh ammo

Opposition to childhood vaccination continues despite the long-debunked theory that vaccines can trigger autism, plus the very real evidence recently of what happens when kids aren't immunized.

Now there's a new study that concludes a combination vaccine commonly used in Canada presents a slightly increased risk of febrile seizures in children.

You can just hear some anti-vaccination advocates: "See, we told you so!"

The study published Monday in the Canadian Medical Association Journal found children receiving the measles-mumps-rubella-varicella (MMRV) vaccine in widest use in Canada, known as Priorix-Tetra, had twice the risk of seizures in the following week to 10 days than those who got two separate injections – one for measles, mumps and rubella (German measles), and the other for varicella (chicken pox).

However, the absolute risk was still very low and was far outweighed by the potential complications from the disease itself, the study noted.

"Despite an increased risk of febrile seizures following MMRV [compared with MMR+V], the absolute level of risk was small," the study's abstract concludes.

"Policy-makers need to balance these findings with the potential benefits of administering the combination vaccine or determine whether the choice of vaccine rests with clinicians and/or parents."

[ Related: B.C. measles outbreak underscores continued battle over vaccination holdouts ]

Yahoo Canada News reached out to the Vaccination Risk Awareness Network, which advocates against compulsory vaccinations and warn about potential risks, but no one responded by deadline to a request for comment on the study.

However, study lead author Shannon MacDonald of the University of Calgary's pediatrics department said in an interview she wouldn't be surprised if anti-vaccinationists took note of her work.

“I’ve dealt a lot with people who are not supportive of vaccines," she told Yahoo Canada News. "So anytime you talk about the safety of vaccines it does trigger an interest in that group."

But if anything, the study should be reassuring for those who think there's a conspiracy to hide the dangers of vaccines.

The fact researchers are publishing adverse findings on risk shows “we’re very serious about vaccine safety and that when there are increased risks we’re informing the public.”

The study's results are actually nothing new, said Dr. Monika Naus, medical director of immunization programs and vaccine-preventable diseases at the B.C. Centre for Disease Control.

While the study focuses on the Priorix-Tetra vaccine, another MMRV vaccine used in Canada has also been associated with febrile seizures in the same order of magnitude of risk, she told Yahoo Canada News.

“The numbers are very similar to the product from the other company," Naus said. “It’s not a surprising finding; it’s not a new finding per se.”

Naus doubted the study will trigger a fresh backlash from the anti-vaccination crowd, which she said remains focused on the supposed autism risk first raised in a 1998 British study based on doctored research.

[ Related: Quebec stands alone in aggressive stance on measles vaccinations ]

Children can experience febrile seizures when they have a high fever. The convulsions can be scary for parents but the usually brief episodes are not the same as epilepsy and have no long-term effects.

MacDonald noted that the risk of a child experiencing a febrile seizure due to the combination vaccine is six or seven in 10,000, compared with 60 to 70 in 10,000 of suffering a febrile seizure due to measles-related fever – a tenfold increase.

"That’s not counting the risk one in a thousand children experience brain swelling from measles and one in a thousand in the developed world die of measles, plus pneumonia and ear infections," she said.

"And that’s just measles disease. Vaccination protects against mumps, which can lead to infertility and deafness, and rubella, that can cause congenital rubella syndrome.

"So the list of bad outcomes from the diseases is just an avalanche in comparison to the snowflake of risk from the vaccine.”

The combination vaccine was developed because many parents did not like the number of needles their children were getting, MacDonald said. Parents who are concerned about the added risk could ask whether their kids could receive two shots instead of one.

Naus said that in British Columbia, pre-school children don't receive the MMRV vaccine.

"So we don’t use it for first dose, we use it for second dose, and for second dose it’s not associated with this risk," she said.

Parents elsewhere in Canada should check with their local health authorities to see what the policy is and whether the MMR+V option is available, she said.

As for the anti-vaccine movement, Naus said the recent measles outbreak in the Abbotsford, B.C., area among a Christian group that doesn't believe in immunization has been a lesson.

"Every outbreak addresses the question that some anti-vaccinationists use to argue against vaccination, which is that we don’t see these diseases in Canada anymore," she said.

"So it’s helpful to have a reminder that if you don’t vaccinate, these diseases come back.”