www.lesswrong.com/posts/H8RdAbAmsqbpBWoDd/canada-lost-its-measles-elimination-st...
1 correction found
The most populous health units, such as Toronto, Ottawa, Halton, Hamilton, Peel, and York, all have three cases or fewer for the entire year, and a corresponding case rate of close to zero.
Public Health Ontario’s table shows those health units had more than three total measles cases in 2025 once non-outbreak cases are included. The post appears to have mistaken outbreak-case counts for total yearly cases.
Full reasoning
Public Health Ontario’s Table 1: Measles Cases by Public Health Unit reports both an outbreak case count and a non-outbreak case count for each health unit.
For the health units named in the post, the official November 13, 2025 summary lists:
- Toronto Public Health: 2 outbreak cases + 7 non-outbreak cases = 9 total
- Ottawa Public Health: 3 outbreak cases + 9 non-outbreak cases = 12 total
- Halton Region Public Health: 2 outbreak cases + 4 non-outbreak cases = 6 total
- City of Hamilton Public Health Services: 1 outbreak case + 3 non-outbreak cases = 4 total
- Peel Public Health: 1 outbreak case + 7 non-outbreak cases = 8 total
- York Region Public Health: 2 outbreak cases + 11 non-outbreak cases = 13 total
So the statement that these health units had "three cases or fewer for the entire year" is incorrect. What is true is that several of them had three or fewer outbreak cases. The PHO report explicitly separates outbreak and non-outbreak cases, and the yearly total is higher when both are counted.
1 source
- Public Health Ontario — Measles in Ontario (Updated November 13, 2025)
Table 1 lists City of Hamilton Public Health Services: 1 outbreak, 3 non-outbreak; Halton Region Public Health: 2 outbreak, 4 non-outbreak; Ottawa Public Health: 3 outbreak, 9 non-outbreak; Peel Public Health: 1 outbreak, 7 non-outbreak; Toronto Public Health: 2 outbreak, 7 non-outbreak; York Region Public Health: 2 outbreak, 11 non-outbreak.