Internet Exposure Associated With Canadian Parents' Perception of Risk on Childhood Immunization: Cross-Sectional Study

"Health authorities need to tackle the negative influence of online vaccine information or communications, and better utilize social media for positive communication to reach and influence vaccine-hesitant Canadian parents searching for information on the Internet."

There are concerns that parental fears or hesitancy on childhood immunisations are increasing in countries like Canada due to the popularity of social media and exposure to online antivaccination sentiment. In that country, the public's confusion and doubt over the measles-mumps-rubella (MMR) vaccine was highlighted by a 2010 study, and several measles outbreaks have been reported across Canada since 2011. This study investigated the potential association between seeking vaccine information on the internet and Canadian parents' perception of risk on childhood immunisation in order to help guide public health interventions.

The Health Belief Model is applied to determine which factors influence individuals when making vaccination decisions. In terms of immunisation, the decision to vaccinate is balanced by the perceived risk of contracting a vaccine-preventable disease and the perceived risk of vaccine-adverse events. Due to the abundance and availability of antivaccination sentiment online and the relatively low prevalence of vaccine-preventable disease in the population, it is suggested that individuals may perceive a greater risk of suffering from vaccination side effects than from contracting a vaccine-preventable disease.

The researchers analysed this association in 2 population samples: a self-selecting Web-based sample of Canadian parents recruited through Facebook (n=966) and a population-based sample of parents recruited by random digit dialing (RDD; n=951). The outcome was parental perception of vaccine safety on a 7-point ordinal scale from "not safe" to "extremely safe". An ordinal regression model was used to investigate if internet information seeking on childhood vaccination predicted parental perception of vaccine safety.

For both data sources, approximately one-quarter of the respondents reported the internet to be a reliable source for information on vaccines or vaccination, and approximately 40% (39.10%, 427/1,092 vs 41.57%, 716/1,729) reported using the internet to search for information on vaccines. In terms of perception on safety of childhood immunisations, 26.77% (292/1,091) of the Web-based survey respondents and 18.74% (324/1,729) of the RDD survey respondents reported childhood immunisations as not at all safe to moderately safe.

After adjusting for income level, internet reliability, age of parent, and region, the odds of perceiving vaccines as less safe rather than more safe were 1.6 times higher (95% confidence interval (CI) 1.3-2.1) for parents who used the internet to search for vaccination information compared to parents who did not search the internet in the Web-based sample, and 2.0 times higher (95% CI 1.6-2.5) in the population-based RDD sample.

The researchers note that the study could not account for the reliability of the websites parents searched or the type of communications they were exposed to on the internet. For example, many Web-based respondents reported using search engines and clicking on the websites from their search results, as opposed to identifying specific websites or types of websites. Several studies have shown an abundance of antivaccination messaging via internet searching (or "Googling") for information on vaccines. In addition, this study did not take into account the respondents' perceptions of risk on vaccine safety prior to the internet search, and it did not examine whether the internet altered prior perceptions of risk or acted to support previously held beliefs. Thus, the researchers cannot establish causality or direction of causality.

However, the findings from both data sources confirm the relationship between looking for vaccine information on the internet and perception of risk on vaccine safety, with both samples revealing higher odds of perceiving vaccines as "not safe" in parents who used the internet to search for vaccine information compared to parents who did not.

The researchers suggest that:

• Governmental and scientific sectors should consider the development and implementation of Web-based vaccine interventions to promote confidence in immunisation.
• Trusted authorities could consider working with popular websites and influential platforms (such as "Mommy blogs") to provide information supportive of immunisation.
• Studies have shown that health communication in the form of stories or testimonials can be an important influence on risk perception and that there is a need for more dialogue-based approaches designed for specific subpopulations.
• There is a need to move away from online communication that involves top-down dissemination of information toward strategies incorporating more complex interaction tools and engagement.