Half of all people who avoid the flu shot do so because they question its importance and effectiveness, a new study from the University of Waterloo reports.

The study reviewed Ontario health data from 2013/14, where only 34 per cent of people went to get the seasonal flu shot despite universal coverage in the province.

“Our research suggests that the majority of people who do not get the flu shot have concerns regarding vaccine effectiveness, or a belief that they have a strong immune system and won’t be affected by the flu,” said Samantha Meyer, a professor in the School of Public Health and Health Systems at Waterloo and the study’s lead author.

The study also found that people avoided flu shots for moral and religious reasons, as well as poor vaccine experiences in the past.

“Unfortunately, many of the responses we heard from participants regarding why they do not get vaccinated were indicative of a very individually focused understanding of the importance of the seasonal influenza vaccine,” said Meyer.

While the degree of protection offered by the flu shot varies each year based on how well the predicted strain matches the actual strain, influenza rates have decreased significantly since the Government of Ontario introduced the Universal Influenza Immunization Program (UIIP) in 2000.

The program, which provides the flu shot free of charge for all individuals over 6 months, has reduced flu cases by 61 per cent and saved $7.8 million in related health–care costs.

“It’s important to look at the health of the population and to recognize the critical role that healthy individuals can play in reducing the risk for the population,” said Meyer. “This is particularly important for vulnerable groups more likely to suffer complications from the flu, including pneumonia, inflammation of the heart and brain, sepsis, and even death.”

In order to provide population–wide immunity from the flu, 80 per cent of healthy individuals and 90 per cent of at–risk individuals would need to get the shot.

Each year, between 10 to 12 per cent of Canadians contract the flu. The illness is responsible for more than 12,000 hospital visits and 3500 deaths.

The study was recently published in the Journal of Health Communication.