Febrile seizures are reported in 2% to 5% of children between the ages of 3 months and 5 years, frequently associated with underlying viral infections, and may follow childhood immunizations. Febrile seizures that are generalized but short-lived (< 15 minutes), and that do not recur within 24 hours are generally considered benign. There is evidence that combination MMRV vaccine products including Priorix-Tetra® (GlaxoSmithKline [GSK] Inc.) and ProQuadTM (Merck Canada Inc.) are associated with a small but real increased risk of febrile seizures in the 7 to 10 days following immunization with the first dose in infancy, as compared to MMR and varicella vaccines administered in separate injections.
Infants age 12 to 47 months receiving their first dose of MMRV vaccines.
Infants aged 12 to 47 months may receive a first dose of MMR and Varicella vaccines separately or the combined MMRV formulation. This consideration will be jurisdiction-specific depending on provincial/territorial immunization recommendations.
With evidence that combined MMRV vaccine products including Priorix-Tetra® and ProQuadTM are associated with a small but real increased risk of febrile seizures following the first dose compared to separate injections, parents need to be counselled and, depending on provincial and territorial immunization programmes, offered a choice of vaccination strategy." - Update on Measles-Mumps-Rubella-Varicella Vaccine and Febrile Seizures