Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Comparative Study
. 2014 Aug 5;186(11):824-9.
doi: 10.1503/cmaj.140078. Epub 2014 Jun 9.

Risk of febrile seizures after first dose of measles-mumps-rubella-varicella vaccine: a population-based cohort study

Shannon E MacDonald  1 , Douglas C Dover  2 , Kimberley A Simmonds  2 , Lawrence W Svenson  2
Affiliations
Comparative Study

Risk of febrile seizures after first dose of measles-mumps-rubella-varicella vaccine: a population-based cohort study

Shannon E MacDonald et al. CMAJ. .

Abstract

Background: The combination measles-mumps-rubella-varicella (MMRV) vaccine currently used in Canada (Priorix-Tetra) may increase the risk of febrile seizures relative to the separate vaccines (MMR and varicella) previously administered. We determined the risk of febrile seizure after the first dose of MMRV, as well as any additional risk for children at high risk for seizures because of pre-existing medical conditions.

Methods: In this retrospective, population-based cohort study, we compared the risk of seizures after the first dose of MMRV with the risk after same-day administration of separate MMR and varicella vaccines (MMR+V) in children 12 to 23 months of age in the province of Alberta. We deterministically linked vaccination data to health service utilization data for seizures. We used Poisson regression, with adjustment for age and calendar year, to determine the risk for the full cohort and for high-risk children.

Results: The risk of seizures 7 to 10 days after vaccination was twice as high with MMRV as with MMR+V (relative risk [RR] 1.99, 95% confidence interval [CI] 1.30-3.05). The excess absolute risk of seizures was 3.52 seizures per 10 000 doses of MMRV relative to MMR+V. In high-risk children, the risk was not differentially higher for MMRV (RR 1.30, 95% CI 0.60-2.79).

Interpretation: Despite an increased risk of febrile seizures following MMRV (compared with MMR+V), the absolute level of risk was small. 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.

PubMed Disclaimer

Figures

Figure 1:
Figure 1:
Incidence of febrile seizure following measles–mumps–rubella–varicella (MMRV) combination vaccine or same-day administration of measles–mumps–rubella vaccine with varicella vaccine (MMR+V). The 7- to 10-day peak risk period is indicated.
See this image and copyright information in PMC

Comment in

References

    1. Summary of European Union decisions on marketing authorisations in respect of medicinal products from 1 June 2013 to 31 July 2013. Off J Eur Union 2013;56(C250):30–43
    1. Klein NP, Fireman B, Yih WK, et al. Measles–mumps–rubella–varicella combination vaccine and the risk of febrile seizures. Pediatrics 2010;126:e1–8 - PubMed
    1. Klein NP, Lewis E, Baxter R, et al. Measles-containing vaccines and febrile seizures in children age 4 to 6 years. Pediatrics 2012; 129:809–14 - PubMed
    1. Statement on measles–mumps–rubella–varicella vaccine. Can Commun Dis Rep 2010;36(ACS-9):1–22 - PMC - PubMed
    1. Routine immunization schedule. Edmonton (AB): Alberta Health; 2013. Available: www.health.alberta.ca/health-info/immroutine-schedule.html (accessed 2013 Dec. 20).

Publication types

Substances