Canada has among the highest COVID-19 vaccination rates in the world, but public health officials are still grappling with question of how to increase vaccine uptake among those who are unwilling to get the jab.

New research emerging from McMaster and McGill Universities provides insight into the reasons and the factors that may lead to vaccine hesitancy among older adults, who are known to be at increased risk of severe symptoms from COVID-19.

The study, published in the American Journal of Epidemiology, analyzed data from nearly 24,000 middle-aged and older adults enrolled in the Canadian Longitudinal Study on Aging (CLSA) about their likelihood of getting the vaccine and the factors associated with COVID-19 vaccine uptake.

The findings represent the largest survey of COVID-19 vaccine willingness among older Canadians to date.

“Our study found that COVID-19 vaccine confidence has been high from the very beginning. Even before COVID-19 vaccines became available in Canada, the majority of older adults were willing to get vaccinated,” said Nicole Basta, an infectious disease epidemiologist, associate professor in the Department of Epidemiology and Biostatistics at McGill and lead author of the study.

The researchers found roughly 84 per cent of adults over age 50 were very or somewhat likely to get a COVID-19 vaccine, while approximately 10 per cent were uncertain and only six per cent were very or somewhat unlikely to receive the vaccine.

The results are similar to current vaccination uptake rates in Canada, suggesting that those who were very or somewhat likely to get vaccinated in late 2020 got vaccinated when eligible. In addition, vaccine coverage rates suggest the majority of people who were uncertain also got vaccinated, whereas those who expressed unwillingness did not.

“Our findings suggest that most people had decided to get the vaccine before it was available and they followed through,” Basta said. “Our study suggests that little headway has been made in convincing the small percentage of people who were unwilling to get vaccinated initially to get vaccinated in the year since vaccines became available.”

The researchers determined that those who were unwilling to receive the vaccine were more likely to be younger (between 50 to 64 years old), female, have lower education and income, be non-white and live in a rural area. Concerns about safety and vaccine effectiveness were the most common reasons motivating those unlikely to receive the vaccine.

The study analyzed CLSA COVID-19 questionnaire data collected in the fall of 2020, before vaccines were readily available.

The research involved a national collaboration of investigators and was overseen by Parminder Raina, the CLSA’s lead principal investigator, along with co-principal investigators Christina Wolfson of McGill and Susan Kirkland of Dalhousie University.

“Ensuring high COVID-19 vaccination rates – especially among older adults who are at increased risk for severe symptoms – is critical,” said Raina, a professor in the Department of Health Research Methodology, Evidence, and Impact at McMaster and the scientific director of the McMaster Institute for Research on Aging.

“Our primary goal was to identify those who would benefit most from targeted outreach to improve COVID-19 vaccine uptake and provide much-needed evidence to inform vaccination programs.”

Previous vaccine history was another important factor associated with COVID-19 willingness. Individuals who had previously received a flu shot or had plans to receive a flu shot were also more willing to be vaccinated against COVID-19.

In addition, willingness was also associated with believing one had never been infected with SARS-CoV-2, the virus that causes COVID-19, as was experiencing negative pandemic consequences.

Funding for the CLSA COVID-19 Questionnaire Study, a sub-study of the CLSA, was provided by the Juravinski Research Institute, McMaster University, the McMaster Institute for Research on Aging, the Nova Scotia COVID-19 Health Research Coalition and the Public Health Agency of Canada.

The overall CLSA research platform is funded by the Government of Canada through the Canadian Institutes of Health Research and the Canada Foundation for Innovation.