biostudies-literatureUnknown19(8)Wright J<h4>Introduction</h4>The incidence of varicella in Canada has decreased by almost 99% since vaccination was introduced. However, variation in the timing and eligibility of vaccination programs across the country has resulted in some cohorts being under-vaccinated and therefore potentially susceptible to infection.<h4>Methods</h4>We used nationally representative specimens from the Biobank of Statistics Canada's Canadian Health Measures Survey (CHMS) as well as residual specimens from Ontario collected between 2009-2014 to estimate population immunity across age-groups and geography, and identify any groups at increased risk of varicella infection.<h4>Results</h4>The weighted proportion of specimens with antibody levels above the threshold of protection was 93.6% (95% CI: 92.4, 95.0). ProtePloS onee0309154https://www.ebi.ac.uk/biostudies/studies/S-EPMC11332944biostudies-literaturePopulation immunity to varicella in Canada: A Canadian Immunization Research Network (CIRN) study.PMC11332944Crowcroft NHatchette TPerez-Iratxeta CSeverini AGubbay JJoh EWilson SEBuchan SAWard BJSerhir BWright JMcLachlan EDeeks SLBolotin SHughes SLBrisson MOsman SHalperin SAfalsePopulation immunity to varicella in Canada: A Canadian Immunization Research Network (CIRN) study.<h4>Introduction</h4>The incidence of varicella in Canada has decreased by almost 99% since vaccination was introduced. However, variation in the timing and eligibility of vaccination programs across the country has resulted in some cohorts being under-vaccinated and therefore potentially susceptible to infection.<h4>Methods</h4>We used nationally representative specimens from the Biobank of Statistics Canada's Canadian Health Measures Survey (CHMS) as well as residual specimens from Ontario collected between 2009-2014 to estimate population immunity across age-groups and geography, and identify any groups at increased risk of varicella infection.<h4>Results</h4>The weighted proportion of specimens with antibody levels above the threshold of protection was 93.6% (95% CI: 92.4, 95.0). Prote2024-01-01T00:00:00Z20242025-05-18T12:13:35.742Z2025-05-18T12:13:35.742ZS-EPMC113329443915921710.1371/journal.pone.0309154