Psychic vs. Economic Barriers to Vaccine Take-up: Evidence from a Field Experiment in Nigeria

"Monetary costs strongly affect vaccination decisions."

Research and experience show that psychic costs of vaccination, which include beliefs and perceptions about vaccines, can influence vaccination decisions. Most existing studies examine barriers to vaccine uptake using qualitative methods, typically by asking respondents their reasons for non-vaccination. This paper presents a causal examination of the relative importance of psychic costs of tetanus vaccination compared to monetary costs among women in rural Nigeria.

The relevance of psychic costs as barriers to vaccination has been documented in Africa (and elsewhere). In northern Nigeria, Islamic leaders boycotted a polio vaccination campaign due to a false rumour that polio vaccines make women infertile or cause them to contract HIV. This distrust of vaccine efficacy led to widespread refusal to receive polio vaccinations among the general population, resulting in increased wild polio virus (WPV) transmission throughout the country and the spread of polio into 20 countries.

This study looks at tetanus toxoid vaccines, which are life-saving and available mostly free of charge in most clinics but do not attain high uptake in Nigeria. It was conducted among 2,530 women of childbearing age in 80 villages in the Jada local government area of Adamawa state in the northeastern region of Nigeria from March-May 2013. The research found, at baseline, that 37.8% of respondents thought they were likely to contract tetanus; on average, they thought that 30 people out of 100 would die of tetanus; and substantial proportions of respondents (35-50%) felt worried about tetanus, thought that tetanus is bad, and felt that it is important to get protected from tetanus. On average, respondents thought that 22 people out of 100 could be saved from tetanus with vaccines.

The randomised experiment captures monetary costs and psychic costs separately as potential barriers to tetanus vaccine uptake. The researchers randomised the amount of cash incentives provided to women whose condition was simply to attend a clinic. To capture psychic costs of vaccination as potential barriers, they gave a group of women their cash incentives with the additional condition of receiving a vaccine at the clinic. Because the only difference between these two conditions is whether a woman was required to receive a vaccine for cash rewards upon arrival at the clinic, the difference in clinic attendance between these two groups captures the psychic costs of vaccination. Furthermore, if those women whose condition for cash provision was clinic attendance refused to take the vaccine after showing up at the clinic, this is directly attributed to the psychic costs of vaccination.

The researchers also examine the effect of priming on vaccination by randomising a disease message: either a "scared-straight" message, which emphasises the severity of tetanus, or a control message, which provides the same information on tetanus without emphasis on the severity of the disease. The message was conveyed to each respondent through a flipchart: one featured frightening pictures of tetanus patients (i.e., the "scared straight" flipchart) and another without such graphic information (i.e., the control flipchart). Priming about disease severity did not alter vaccine uptake, but it did increase the perceived severity of disease, as well as respondents' heart rate.

The primary contribution of this study to the literature, according to the researchers, is to develop a novel experimental design causally detecting psychic costs of vaccination. (See the full paper for the empirical model.) For clean identification of psychic costs, they narrowly define them, sacrificing the external validity of the findings. (The experimental design cannot detect other potentially significant psychic costs, such as distrust of healthcare providers.)

Contrary to the emphasis on psychic costs in observational studies, the researchers do not find that psychic costs of vaccination are large barriers to vaccination. The clinic attendance of women who were offered cash compensation for a clinic visit but not required to receive a vaccine did not differ from that of women who were required to get vaccinated at a clinic in order to receive the same compensation. Furthermore, almost all women (95.7%) actually received a vaccine upon their arrival at clinics, even when it was not necessary in order to receive cash rewards.

However, due to several limitations in the experimental design and implementation, the researchers "cannot eliminate the possibility that psychic costs of vaccination are barriers to vaccination. Since the significance of psychic costs determines effective policies to promote vaccination, developing better ways to capture psychic costs is much needed. For example, a better research design might be to conduct door-to-door vaccination to eliminate the psychic costs of clinic attendance. Either way,...[this] study highlights the importance of behavioral experiments in studying psychic costs."