Vaccination rates are slipping around the world. Canada isn't immune, says new study

After decades of progress, childhood vaccination rates have started stalling or falling around the world in recent years, and Canada is not immune to the trend, suggests a new study from The Lancet.

The study estimated the coverage of 11 childhood vaccines in 204 countries and territories between 1980 and 2023, analyzing over 1,000 data sources from around the world.

It found that although globally there were huge strides made in vaccine coverage for children during that period (vaccine coverage against diseases like measles, polio and pertussis more than doubled), progress started stalling, even before the COVID-19 pandemic.

"Particularly in the Americas and high-income countries, between 2010 and 2019, measles vaccine coverage declined in about half the countries," said Dr. Jonathan Mosser, an assistant professor of health metric sciences at the Institute for Health Metrics and Evaluation at the University of Washington and one of the co-authors of the study.

The pandemic dealt a heavy blow to vaccination rates, with more than 15 million children globally missing routine shots between 2020 and 2023, Mosser said.

The world never fully rebounded to pre-pandemic childhood vaccination levels, he said. 

"The pandemic reversed decades of progress that we had in reducing the number of zero-dose children, those children that have never received one of these key childhood vaccines."

The pandemic had an outsized impact on regions that already had low vaccine coverage before COVID-19, Mosser said. 

Countries in sub-Saharan Africa saw the greatest disruption to vaccine coverage: five to seven million children in the region are estimated to have missed vaccines protecting them against diseases like polio, pneumococcal disease and rotavirus. 

"We have challenges related to really long-standing global inequalities and vaccination coverage with many low- and middle-income countries having significantly lower coverage than high-income countries," Mosser said. 

Why vaccination rates have started stalling varies from country to country, he added.

"In some places around the world, they're related to geopolitical instability, they're related to supply chain issues. In many high-income countries, they're related to vaccine misinformation and hesitancy," he said. 

In Canada, Mosser said, vaccine coverage for most shots has dropped compared to the early 2000s. Uptake for some vaccines have fallen over time, like the shot that protects against diphtheria, tetanus and pertussis. Recently there's been some increases in uptake for other jabs – like the first dose of the measles, mumps and rubella (MMR) vaccine — but the modest increase isn't enough to prevent outbreaks.

For instance, Mosser said, vaccination rates for measles in 2023 — 92 per cent for one dose of the MMR and 79 per cent for two doses of the MMR — are well below the threshold needed for herd immunity, which is 95 per cent.