Table 1. Summary of measles outbreaks in Canada (N=6), by earliest date of rash onset, 2018.

Outbreak number	Province/territory	Number of cases	End date of epidemiologic week of rash onset of index case	Genotype (Strain)a	Description
1	Quebec	4	April 15	B3 (MVs/Dublin.IRL/8.16/)	The index case reported travel to Romania during the exposure period. Three secondary cases among family contacts of the index case were subsequently reported. All of the cases were unvaccinated.
2	Alberta	2	May 13	D8	The index case reported travel to India during the exposure period. One secondary case, a close contact of the index case, was subsequently reported. The vaccination history of the index case was unknown. The secondary case was unvaccinated.
3	Ontario	2	June 3	D8 (MVs/Gir Somnath.IND/42.16/)	The index case reported travel to Ukraine during the exposure period. One secondary case, a close contact of the index case, was subsequently reported. The vaccination history of the index case was unknown. The secondary case was unvaccinated.
4	British Columbia	2	August 26	D8 (MVs/Osaka.JPN/29.15/)	The index case did not report travel outside of Canada during the exposure period, but was potentially exposed to an international measles case at a Canadian port. One secondary case, a contact of the index case, was subsequently reported. Both cases were fully vaccinated.
5	Manitoba	2	September 9	D8 (MVs/Samut Sakhon.THA/49.16)	The index case reported travel to Southeast Asia during the exposure period. One secondary case, a close contact of the index case, was subsequently reported. The index case was unvaccinated. The secondary case was fully vaccinated.
6	British Columbia	2	November 4	B3	The index case reported travel to the Philippines. One secondary case, a contact of the index case, was subsequently reported. The vaccination history of the index case was unknown. The secondary case was fully vaccinated.

^a World Health Organization (WHO)-named strain, in brackets, if applicable. WHO-named strains represent a system to reflect currently circulating epidemiologically significant lineages of measles viruses within the existing genotype classification system. This enables tracking of global transmission pathways (12). The strains are defined within the Measles Nucleotide Surveillance (MeaNS) database and represent a lineage, a precisely defined virus strain, that has been frequently detected within a two-year period in multiple countries. GenBank accession numbers for the named strains are KY013331, KY120864, LC072667 and MK079566