Researchers In The Making
Why not vaccinate?
An AHFMR Student explores the reasons parents don't immunize their children.
Story by Tara Narwani/Photo by Laughing Dog
No parent would want a child to contract diphtheria. The bacterial infection produces a fuzzy grey-black coating in the throat that could cause a child to choke and even die. Fortunately, no one in Canada has died from the disease since 1983 due to the implementation of vaccination programs.
The success of these programs depends, however, on the degree of public support they receive. Registered nurse Shannon MacDonald, an AHFMR-supported Ph.D. student in the Faculty of Nursing at the University of Alberta, is alarmed by recent trends in vaccination rates. For her doctoral work she will examine why certain parents take their children for only some of the recommended vaccinations or do not have them vaccinated at all.
Recent data from the Capital Health area show that only 85% of 2-year-olds have had all of their DTaP-IPV shots, the series of injections that includes the vaccine against diphtheria. A coverage rate of 85% might sound high, but it's significantly lower than the 95% level required for a population to achieve "herd immunity".
Herd immunity occurs when immunization levels are so high that there is very little chance that the small portion of the population who are not immunized will come in contact with the disease. "Herd immunity is what's required to keep these horrific diseases at bay," MacDonald explains. It prevents an infection from spreading like a chain reaction, and it protects individuals who can't be vaccinated for medical reasons such as those whose immune systems are compromised.
If vaccination rates are too low, diseases that were thought to have been eradicated can reappear, with fatal consequences. "When the former USSR fell apart, so did its public-health system. They had huge outbreaks of diphtheria. In 1989 [prior to the dissolution of the Soviet Union] they had 839 cases of diphtheria; in 1994 [after the country had split] the independent states reported 50,000 cases, and 1700 deaths," MacDonald recounts.
In the Capital Health area, only two of the six routine vaccinations for 2-year-old children have coverage rates that approach 95%. The remaining four range between 84% and 87%. During her clinical work in a pediatric intensive-care unit, Shannon MacDonald saw the very real consequences of decisions not to vaccinate children. "We would see kids, for instance, with Haemophilus influenzae type b meningitis because the parents hadn't immunized. It wasn't common, but it occurred."
These experiences inspired MacDonald to investigate the factors that influence parents when they're deciding whether or not to complete their children's routine vaccinations.
Previous studies, conducted in the United States, indicate that parents refuse vaccination for their children because of fears around vaccine safety. Certainly there has been considerable debate about whether childhood vaccines can be linked to the incidence of autism, but numerous studies have proven that there is no connection.
MacDonald points out that the US context is very different from that in Alberta and, indeed, in most of Canada. If American parents want to decline vaccinations for their children, they have to take steps to opt out of a mandatory program; and they likely wouldn't expend the effort to do so unless they had strong objections.
In Alberta, where the system is voluntary, she suspects that there are additional factors influencing parental choice. "Is it that parents have beliefs that prevent them from immunizing their children? Is it that they have to take time off work, and they can't afford to do that? Or that they go to the clinic and their healthcare provider is dismissive of their concerns?"
To identify these influencing factors, MacDonald will compare the experiences of parents who completed their children's vaccinations at the two-year mark with those of parents who did not. Parents in the Capital Health region will be asked to complete a mail survey that could include questions such as these: "When you phoned to make an appointment, were you offered a time that was convenient? When you went for the appointment, was the nurse able to answer your questions? Did you have trouble remembering when the immunization was due?" MacDonald will collaborate with Capital Health to identify potential participants, who will receive the final questionnaire in the summer of 2009.
MacDonald's goal is to see vaccination rates increase significantly. In order for this to be achieved, the barriers to vaccination must be correctly identified.
"If we had unlimited resources, we would say, Here's the whole grocery list of possible reasons [why parents don't vaccinate]-let's just address them all," MacDonald says. "We'll educate all the providers. We'll educate all the parents. We'll have the clinic open 24 hours a day. But we don't have unlimited resources. We'll have to target the main issues."