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Vaccine hesitancy becomes a top global health threat

The anti-vaccination movement has succeeded in creating a new global health emergency right alongside the existing threats of influenza pandemic, microbial resistance, the Ebola virus, HIV, pollution and climate change, and non-communicable diseases such as obesity, diabetes, and heart disease.

Vials of measles, mumps and rubella (MMR) vaccine are displayed on a counter at a Walgreen store. Credit: Justin Sullivan/Getty Images

In January 2019, World Health Organization (WHO) announced the top 10 threats to human health that require immediate attention and action. Among these threats, vaccine hesitancy is making headlines all around the world, with news about recent outbreaks of measles in the United States, Europe and Asia. This week, a new outbreak was reported in the Philippines, where there were 4,302 reported cases in January alone, a record-breaking high for the country. The growing spread of a highly infectious and life-threatening disease like measles around the world is disconcerting, as the rates of infection can be significantly reduced and even fully eliminated through vaccination with two doses of the measles, mumps and rubella (MMR) vaccine.

In the United States, five outbreaks have been reported since the beginning of the year in the states of New York, Washington and Texas. As of today, there are 62 confirmed cases in the state of Washington, where the Governor had declared a public health emergency. What makes the situation urgent is that it takes time when an individual is infected with the measles virus to show symptoms of the disease, which is known as the incubation period. During the incubation period, individuals are likely to interact with others and spread this highly contagious disease. According to the Centre of Disease Control and Prevention (CDC), the United States eliminated measles in the year 2000 through decades of widespread vaccination using the MMR vaccine, which was initially introduced in 1963. Vaccine hesitancy and the growing rate of unvaccinated children is one of the major reasons this disease is now coming back in places like the United States and other countries with high vaccination rates.

The WHO Strategic Advisory Group of Experts (SAGE) defines vaccine hesitancy as “a delay in acceptance or refusal of vaccines despite availability of vaccination services.” Taking the Philippines as an example, immunization has dropped from 88% in 2016 to 73% in 2017. This decline is primarily due to the parents unwillingness to vaccinate their children despite resources being readily accessible. As seen in the state of Washington and other places, people have the choice to opt themselves and their children out from receiving these critical vaccines, solely based on personal beliefs. What is most alarming about vaccine hesitancy that it is driven by individual beliefs about the safety of vaccines, rather than lack of access to vaccines and immunization services. The WHO determines vaccination as one of the most cost effective ways to combat diseases, which currently prevents 2-3 million deaths every year. Over 1.5 million deaths can be avoided by the use of vaccines, but it seems the most complex aspect is convincing vaccine hesitant individuals that vaccines prevent diseases efficiently.

The birth of anti-vaccine movement can be traced back to a widely debunked theory by the former British gastroenterologist Andrew Wakefield that the MMR vaccine causes autism. In 1998, Wakefield and his colleagues published an article suggesting a link between the MMR vaccine and autism, which quickly gained popularity and stirred a controversy in the medical community. Shortly after, its findings were found to be fraudulent and the paper was eventually retracted in 2010. Wakefield used insufficient data that violated ethical regulations and was inappropriately influenced by his own financial motives. Although this article was retracted and following studies proved there was no link between autism and vaccination, it seems that fear surrounding vaccines persisted. It is not just the measles, mumps, and rubella (MMR) vaccine that people are currently refusing. There has also been a decline in the uptake of the human papillomavirus (HPV) vaccine due to safety concerns. People's fears, however, are not justified, as extensive research on the safety of the HPV vaccine has shown that adverse effects are extremely rare and occur in one per million cases. On the other hand, HPV itself contributes to 5% of the global cancer burden. Benefits significantly outweighing risks in this case, and choosing to remain unvaccinated leaves individuals vulnerable to preventable diseases. In 2019, the WHO is making it their mission to increase HPV vaccine coverage in efforts to eliminate cervical cancer.

Vaccine hesitancy is a complex phenomenon that can be understood as a spectrum of attitudes and behaviors towards vaccines. A 2016 study by Angus Thomson and colleagues proposes a “5A” system (access, affordability, awareness, acceptance and activation) to determine vaccine uptake. Although access and affordability is not a problem in the developed countries, more needs to be done to increase awareness and outreach about the importance of vaccination and specific types of vaccines. This is due to that fact that many people tend to accept some vaccines, while refusing others. They are more willing to receive a vaccine for deadly and severe conditions like H1N1, rather than a regular influenza vaccine. Nonetheless, there are people who can access, afford, and accept vaccines, but still opt out of immunization. This is where the fifth dimension of activation comes into play. Activation refers to being encouraged to get vaccinated. This can take the form of constant reminders or public health policies. Thomson’s study shows that institutions like workplaces and schools with vaccination policies in place have a higher success rate of getting people immunized.

The growth of anti-vaccination movement indicates that trying to convince individuals about the efficacy of immunization may not be enough. Rather, it seems that people must be bound by mandatory vaccination policies or at least regularly prompted to get vaccinated. One ray of hope is that the recent measles outbreaks are encouraging minors in the United States to become activists for vaccination, despite their parents being against it. However, more policies need to be put in place to allow for this to happen, especially in areas where people can easily refuse vaccines. With the WHO declaring vaccine hesitancy as a top threat to global health and recent outbreak emergencies, establishing stronger policies to encourage optimal levels of immunization can be an effective solution to vaccine hesitancy, particularly in developed countries.

Nikkita Mistry is a science writer at the Canadian Institute for Genomics and Society. She is completing the Honours Life Sciences Program at McMaster University and is passionate about science and knowledge translation.

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