The new study found that 1 year olds who were given a single shot of Priorix-Tetra — the MMRV vaccine used in Canada were twice as likely to get fever and seizures as those who were given an MMR shot and a separate Chickenpox shot.
The findings are similar to a prior study on the MMRV vaccine used in the United States, known as ProQuad done in 2010. Parents in the US now have to specifically as for MMRV if they want their toddler to be given the shot, said Dr. Nicola Klein who led this study.
But even if there is an increased risk of fever-induced seizure, parents should note that the odds are extremely low.
And the seizures aren’t dangerous, “though they are scary for parents,” said Klein, co-director of the Kaiser Permanente Vaccine Study Center in Oakland, Calif.
The doctor stressed that without the vaccination the children were much more likely to get a high fever and seizures with measles and that was a greater risk to take.
“Get your child vaccinated,” she stressed. “We’re in the middle of a 20-year high in measles cases.”
Shannon MacDonald, a post-doctoral fellow at the University of Calgary in Alberta, Canada, who led the new study said that it wasn’t clear why the single shot induced more seizures than the MMR and chickenpox separate shots.
But most doctors believe that the combined effect triggers the immune system response and a higher fever in some children which may lead to seizures. Whether due to infection or vaccination, seizures are due to the body’s immune system response.
The new research was published yesterday in the journal CMAJ (Canadian Medical Association Journal), and is based on records for almost 278,000 Alberta children between the ages of 12 and 23 months. All these children received either a single shot or two separate MMR and chickenpox shot on the same day.
The researchers observed that the seizure rates reached its peak after seven to ten days of vaccination. There were almost six seizures for every 10,000 doses of the MMRV, versus two seizures for every 10,000 doses of the separate vaccines.
“You see the same increase in risk with these different formulations,” said MacDonald, referring to the Priorix-Tetra and ProQuad vaccines.
The two separate shots therefore seem safer.
“There’s no question children should be vaccinated,” MacDonald said.
Since the beginning of 2014 through to May 30th the U.S. Centers for Disease Control and Prevention has received reports of 334 measles cases from 18 states. Almost all of these have been unvaccinated U.S. residents who traveled to countries where measles is common, then brought the virus home with them.
Measles symptoms may include fever, cough and a body wide rash. It can also lead to serious complications. The CDC notes that five percent of the infected children may develop pneumonia, and one in thousand suffer brain inflammation. And for every 1,000 children who develop measles, one or two will die.
Macdonalds said that parents should be aware that MMRV may lead to higher seizure risks and consult their doctors before getting a vaccination. She added that some parents may still prefer the single shot to prevent their child from getting two painful shots.
Based on the ProQuad study, the U.S. Advisory Committee on Immunization Practices changed its stance on the MMRV. Now it is up to the parents to decide if they want to get the MMRV shot. Doctors now give the two separate shots only.
For the second dose of the same vaccination though, which is given between 4 and 6 years of age, fever induced seizures are very uncommon and the combined MMRV shot is a better option.
