Background: Measles has been eliminated in Canada since 1998. Every year, the Public Health Agency of Canada presents epidemiologic evidence to the Pan American Health Organization (PAHO) to verify that measles continues to be eliminated in Canada. The objectives of this article are to: provide an epidemiologic summary of measles activity reported in 2018 in Canada, and provide documented evidence to support the continued verification of measles elimination status in Canada.
Methods: Measles surveillance data were captured by the Canadian Measles and Rubella Surveillance System (CMRSS) and descriptive analyses of demographics and risk factors were performed. Outbreak characteristics were summarized and genotypic analyses conducted. Surveillance data for 2018 were evaluated against PAHO's essential criteria for measles elimination status.
Results: In 2018, 29 measles cases were reported across five provinces in Canada, an incidence rate of 0.8 cases per 1,000,000 population. Of these 29 cases, 16 were imported and five resulted in further transmission within Canada. The age-specific incidence rate was highest among those aged younger than one year (10.2 cases per 1,000,000 population, n=4). Only nine cases were considered up-to-date for measles vaccination, and 11 cases were hospitalized. Genotype information was available for most of the measles cases (n=27); they were all found to be genotypes that circulated globally in 2018. Canada met or partially met three out of four of PAHO's criteria for verification of measles elimination.
Conclusion: Although importations and areas of low vaccination coverage continue to challenge Canada's elimination status, there is no evidence that endemic transmission of the measles virus has been re-established. Canada maintains its measles elimination status.
Keywords: measles; measles elimination; surveillance; travel health; vaccination.