What does vaccine coverage really mean?
In my work, I look at one number a lot: vaccine coverage. It answers one question. Out of all the children of a certain age, how many got a certain vaccine?
Say a town has 100 seven-year-olds, and 90 of them got both measles doses. Coverage is 90 out of 100, or 90%.
Look for three things
- Which vaccine? Each vaccine has its own number.
- How many doses? Measles needs two. In 2025, around the world, 84% of children got the first dose, but only 77% got the second.
- By what age? Coverage is checked at set ages, like 2 and 7. A late shot counts as "not covered" at the first check.
Why 95%?
Measles spreads very easily. When about 95 out of 100 people are protected, measles cannot find enough people to spread to. This also protects babies who are too young for the vaccine. Canada's goal is 95% coverage for childhood vaccines by age 2 and by age 7.
Where Canada stands
A study of four provinces and Yukon found that two-dose measles coverage at age 7 dropped from 86.3% in 2019 to 75.6% in 2023. That means about 1 in 4 children were missing a dose.
Averages hide gaps
A province's number is an average. In Alberta, one area had almost 95% of children with two doses by age 7. Another area two hours away had only about 1 in 4. Measles finds these low spots.
What the number does not say
Coverage tells us how many children got a vaccine, not why some did not. Maybe the clinic was far away. Maybe a parent had questions. To close a gap, we need to listen to families, not only count.
Sources
- Public Health Agency of Canada. Vaccination coverage goals and vaccine preventable disease reduction targets by 2025
- Routine vaccination coverage at ages 2 and 7, before, during, and after the COVID-19 pandemic: results from the STARVAX surveillance system Canadian Journal of Public Health. 2024. doi:10.17269/s41997-024-00956-9.
- McKay B. Can Alberta hit Canada's 2025 childhood vaccination targets? St. Albert Gazette (Local Journalism Initiative).
- UNICEF and WHO. Global childhood immunization coverage inches forward despite conflict and hesitancy July 2026.
- World Health Organization. Measles fact sheet
