Psychological costs are significant barriers to vaccination among women in the northern Nigeria and they reduce the vaccination rate significantly. That is the key finding of the research by Ryoko Sato.
The research uses a field experiment to prove that psychic costs of vaccination – such as fear of side effects, fear of needles and distrust of the efficacy of vaccines – reduce take-up among Nigerian women by 13.7 percentage points.
The results also indicates that vaccine take-up by some of these reluctant recipients can be easily increased through a simple intervention such as a door-to-door campaign. But for the rest of who refuse to receive the vaccine even though they are offered the vaccine at their house, more fundamental intervention to increase their perceived benefits of vaccine seems necessary to change their behaviour.
Conventional wisdom emphasises the importance of psychic costs as one of the major barriers to vaccination. The well-known example of psychic costs of vaccination is the polio vaccine boycott that took place in the northern Nigeria in 2003. Islamic leaders publicly opposed the polio vaccine campaign, stating that the vaccines might make women infertile or cause them to contract HIV. It is believed that this movement led to a widespread refusal of polio vaccinations domestically and resulted in the spread of polio throughout the country as well as to 20 neighbouring countries.
But no causal studies have systematically examined this conventional wisdom. This study employs an innovative field experiment to prove the importance of psychic costs of vaccination as one of the major barriers to vaccination.
The research focuses on tetanus-toxoid vaccine, which is the most effective way to prevent neonatal tetanus. Neonatal tetanus is often contracted when the umbilical cord of women in labour is cut with a non-sterile instrument, and it is a significant cause of neonatal mortality in Nigeria.
The research evaluates the significance of psychic costs of vaccination among women at childbearing age who never received tetanus-toxoid vaccines in the northern Nigeria.
Here is how the study causally detects the psychic costs of vaccination among women. On the one hand, the study randomly selected eligible women as a control group, and asked them to answer very simple questions about tetanus-toxoid vaccine.
On the other hand, the study offered an opportunity to the women who were randomly selected to be in the treatment group to receive a tetanus-toxoid vaccine, on top of asking them to answer the same simple questions as we did for the control group.
Among women in the control group, 94% of them agreed to answer the simple questions. Among women in the treatment group, 80.3% of them expressed their willingness to receive the vaccine and took the vaccine, in addition to answering the simple questions. Thus, psychic costs of vaccination reduce the vaccine take-up by 13.7 percentage points.
Some women in the treatment group first did not express their willingness to receive the vaccine, but once offered the vaccine at their house, they decided to receive it. As a result, it increased the acceptance rate among treated women from 80.3% to 85.5%.
This result implies that although psychic costs of vaccination reduce the vaccine take-up by 13.7 percentage points, 5.2 percentage points of vaccine take-up can be easily increased through a simple intervention such as a door-to-door campaign.
But for the rest of the 8.5 percentage points who refused to receive the vaccine even though they were offered the vaccine at their house, more fundamental intervention to increase their perceived benefits of vaccine seems necessary to change their behaviours toward vaccination.