Measles surveillance in Canada, 2019

Abstract

Background: The Public Health Agency of Canada (PHAC) has conducted enhanced measles surveillance since 1998, the year endemic measles transmission was eliminated in Canada. The objective of this annual national measles surveillance report is to provide an epidemiologic summary of measles activity reported in Canada for 2019 in order to provide evidence to support the continued verification of Canada’s measles elimination status. Methods: Measles surveillance data are housed in the Canadian Measles and Rubella Surveillance System (CMRSS) database. Descriptive analyses of demographics and risk factors were performed. Outbreak characteristics were summarized and genotypic analyses conducted. Surveillance, laboratory and vaccine coverage data for 2019 were used to assess Canada’s status against the Pan American Health Organization (PAHO) essential criteria for the verification of measles elimination. Results: In 2019, 113 measles cases were reported in Canada (crude incidence rate of 3.0 cases per 1,000,000 population). Of these cases, 42 (37%) were imported into Canada, and of the imported cases, 12 (29%) resulted in further transmission. Infants younger than one year had the highest age-specific incidence rate at 13.1 cases per 1,000,000 population. Only 29% of cases had one or more documented doses of measles-containing vaccine. One-fifth (19%) of cases were hospitalized; no deaths were reported. Genotype information was available for 100% of outbreaks reported in 2019 and 90% of non-outbreak-related measles cases; of cases with genotype information available, 27% were B3 and 73% were D8. Conclusion: Despite meeting/partially meeting only three out of four of PAHO’s essential criteria for measles elimination status, there is no evidence that endemic measles transmission has been reestablished in Canada.

Measles

“…Most measles cases in Canada occur in unvaccinated people, especially children. 4 Routine childhood vaccines missed during the COVID-19 pandemic should be caught up urgently. Vaccine coverage of at least 95% with 2 doses of measles-containing vaccine among age-eligible children is required for population immunity.…”

Genome sequence of a measles virus strain with a novel loss of stop codon mutation in the phosphoprotein gene

“…1A ). An MeV coding-complete genome sequence [MVs/British Columbia.CAN/4.19 (B3)] with a novel phosphoprotein (P) gene mutation was obtained from a urine specimen and collected from a measles case occurring in 2019, as part of the Canadian national measles surveillance program ( 3 ).…”

Monitoring real-time transmission heterogeneity from incidence data

“…Here we followed this assumption and applied the IIH model and instant-level model to the incidence data over the same period to get the overall estimation of k and R, which were compared with the corresponding records in literatures. We also calcuated the overall estimation of transmission transmission heterogeneity of measles epidemic in Canada during 2019 [35] and compared with the recorded heterogeneity of measles epidemic in Canada from 1998 to 2001 [1]. This comparison is not formal since the analyzed data and the recorded heterogeneity came from two epidemics.…”

“…In addition, we analyzed the dispersion number of the measles outbreak in Canada between 2019-01-01 and 2019-08-31 [35]. With the IIH model, we estimated the dispersion number k as 0.94 (95% HPD: 0.22�7.47), which is overlapped with the recorded result on k (i.e.,90% CI 0.12�0.65) in Canada from 1998 to 2001 [1].…”