A Behavioral Economics Approach to the Failed HPV Vaccination Program in Japan

Drawing on behavioural theories, this commentary asks, Why did Japan's human papillomavirus (HPV) vaccination programme almost come to an end in 2014 following media reports of adverse vaccine events? After the Ministry of Health, Labour, and Welfare (MHLW)'s urgent programme to protect youth against cervical cancer achieved an HPV vaccination rate in 2011/2012 approaching 70% in its targeted group of girls aged 12-16, allegations of adverse medical events following vaccination and the anti-HPV-vaccine publicity that followed led the rate to fall drastically to under 1%.

The World Health Organization (WHO) responded by offering consistent support for the safety and efficacy of the vaccine, and an epidemiology report found that the alleged adverse vaccine effects were only background medical conditions found in all young girls of the intended age group and occurred unrelated to receiving the vaccine. Although the national government's proactive recommendation has been suspended, local programmes for HPV vaccination have continued to be available, and girls aged 12-16 do not need to pay for HPV vaccination. So, this commentary also asks, Why have mothers decided to not have their children vaccinated?

According to data provided in a report released in 2014 by Japan's MHLW's 10?th Health Science Council, among the 8,898,000 HPV vaccinations administered in Japan, the occurrence of severe adverse events was 0.007%. Meanwhile, the number of cervical cancer cases in Japan was 10,908 (in 2012), and the number of deaths due to the disease was 2,902 (in 2014). The HPV vaccine is known to be able to decrease cervical cancer cases by as much 60-70%, and lifetime risk for it ranges from around 1% to around 0.3–0.4%. "While all these values provide information about 'risks' at a general population level, it is very difficult to translate this kind of information into 'risk at the level of individual' that the general population can be encouraged to grasp and assess rationally."

Figure 1 in the commentary shows perception of the value of a "block of information" by the "probability weight function" of the Prospect Theory. The factoid, "There is a very low probability of adverse events, 0.007% (7 per 100,000 vaccinations), associated with HPV vaccination", is overvalued, and the information block, "There is a high probability (70%) of prevention of cervical cancer and a higher rate of reduction of lifetime cervical cancer risk from around 1% to around 0.3-0.4% by being vaccinated against HPV" is undervalued, by the "probability weight function" in the Prospect Theory. According to "availability heuristics", media reports of so-called adverse events became the "more available" information for decision making, thus were overvalued by the "probability weight function", acting as a high wall to hide the benefits of cervical cancer prophylaxis, rendering mothers unwilling to have their daughters vaccinated, resulting in the behaviour selection of not receiving the vaccine.

Looking ahead, the authors suggest that behavioural economics teaches us that a situation of "limited and negative information" can be avoided or surmounted by changing how such information is provided. This can help to better address the selection of thoughts and behaviours by humans, who are not necessarily reasonable. What is called for is providing the intended audiences with scientifically correct information, in this case about HPV vaccinations, as well as information on the extreme negative aspects of getting cervical cancer and the advantages of cervical cancer prophylaxis via HPV vaccination, with the goal that now this information comes to mind first when mothers are making their future vaccination decisions.

Specifically, they "believe that it will be vital to repeatedly broadcast correct and favorable information about the safety and efficacy of the HPV vaccine, as well better educating the public about the significant risks to health, life and fertility from cervical cancer. These messages need to be delivered in an appropriate way as broadly as possible, coinciding with when a governmental recommendation is resumed, so the messages are as 'fresh' as possible. When there is a renewed recommendation, it must take into consideration the irrationality that human beings often take 'moderately' unreasonable behaviors, as pointed out by behavioral economics. If our policy makers make this allowance, the number of mothers who decide to encourage vaccination for their daughters should increase..."