Preventing Erosion of Oral Polio Vaccine Acceptance: A Role for Vaccinator Visits and Social Norms

"[C]ommunication and community engagement efforts need to focus not only on persuading the small fraction of parents and other caregivers who are not accepting OPV today, but also on preventing erosion of OPV acceptance among caregivers who have been accepting it previously."

In light of the prolonged timeline for polio transmission interruption in Pakistan, there is concern that caregivers who have been accepting oral polio vaccine (OPV) to date will become fatigued or frustrated with frequent door-to-door vaccination campaigns, particularly in high-risk communities that lack other essential health services. (Because a child must receive multiple doses to generate a sufficient immune response, a family can experience as many as 12 campaigns per year.) Drawing on data from a poll of parents and caregivers in such areas, this study explores whether social norms may be protective against vaccination decline in Pakistan and, if so, how these norms might be incorporated into strategic communication to prevent OPV acceptance erosion.

As the researchers explain, evidence from other contexts suggests that people are more likely to get vaccinated themselves or have their children vaccinated if they believe that others in their social group commonly do the same (descriptive norms) or believe that their peers support vaccination broadly (subjective norms). This logic may be particularly applicable in the case of OPV in Pakistan, because vaccinators move from door to door and visibly mark their visits on doorways with chalk. Further, neighbours might reasonably assume that if they have positive experiences with the vaccinator and accepted the vaccine, their neighbours also have accepted the vaccine. If this kind of thinking does happen, enhancing interactions with vaccinators could be a promising strategy not only for increasing vaccine acceptance at the moment of the visit but also for promoting the social norms that could prevent acceptance erosion going forward.

Data were analysed from a poll conducted by local gender-matched interviewers between February 23 and April 5 2016 among 4,070 parents and other caregivers of children under age 5 living in areas at high risk for polio transmission in Pakistan. The sample was drawn via a stratified multistage cluster design utilising random route methods at the household level. The researchers examined the relationship between these social norms and vaccination behaviours, as well as the relationship between experiences with and views of vaccinators and social norms using uncontrolled comparisons (t-tests of proportion) and logistic repressions to control for demographics.

Key findings:

• 93% of caregivers said they had accepted OPV for their child every time it was offered in the past year; 97% said they intended to accept OPV for their child "every time it is offered" until they reached age 5.
• 66% of caregivers held positive descriptive social norms, saying that "all" their neighbours accepted OPV ("polio drops") every time it was offered, while 34% said not all of the neighbors accepted OPV every time it was offered.
• 56% of caregivers held positive subjective social norms, saying they thought their neighbours thought giving OPV to children in the neighbourhood was a "very good" idea, and 62% said they believed that their friends thought it was a "very good" idea.
• Caregivers who held positive social norms were more likely to say their child received the vaccine every time it was offered in the past year, as compared to those who held negative norms (96% vs. 88%). The same pattern held true with regard to commitment to vaccinate: Those who held positive social norms were more likely to say they intend to accept OPV for their child every time it is offered until the child is 5 years old, as compared to those who held negative social norms (98% vs. 94%).
• Among caregivers who saw or talked to vaccinators in the last campaign, 68% said they trusted the vaccinator(s) "a great deal", while 30% said they trusted them "somewhat". Those who trusted the vaccinators "a great deal" were more likely to say they thought all their neighbours accept OPV every time offered, as compared to those who had less trust in the vaccinators (71% vs. 60%).

The researchers note that their two hypotheses are supported by the findings, offering some thoughts on ways forward:

1. Positive social norms are positively associated with vaccine acceptance and commitment to vaccinate in future. Implications include:
   • Social norms are more variable in the population than reported acceptance or commitment. That is, fewer people say all their neighbours accept OPV every time than say they themselves accept OPV every time. Thus, this measure of social norms could be a useful marker for risk of acceptance erosion when acceptance and commitment are so high.
   • The discrepancy between the fraction of caregivers who think their neighbours accept the vaccine and those who personally do suggests more people could be made aware of the norm of high acceptance in their community. Communicators could create related messages that would be shared through social and mass media approaches. Communication strategies may also include layered approaches that incorporate direct communication, as the vaccinator may explicitly share messages about how high vaccination rates are in the community.
2. Positive experiences with vaccinators are associated with both descriptive and subjective positive social norms. Implications include:
   • Communication tactics may need to attend more closely to the relationship with vaccinators and the vaccinator experience. As the findings indicate (see, e.g., Table 5 in the paper), enhancing the vaccinator experience by increasing trust, the degree to which parents feel the vaccinator genuinely cares about the child, the perceived competence of the vaccinator, and the features of the visits so they are least disruptive to families could help bolster social norms that protect against acceptance erosion. A specific suggestion related to increasing trust: Ensure vaccinators reflect characteristics more likely to be trusted (e.g., older women or men who hail from the community itself).
   • It may be important to consider ways in which the vaccinators themselves are supported. In light of serious challenges they have faced, including harassment and assault, attention to the needs of vaccinators - including not only security but also their sense of being valued through training, mentorship, and pay - becomes paramount.

The researchers suggest that this study's findings on the importance of social norms, and the role providers may play in bolstering them, may be applicable to other contexts where repeated vaccinations (OPV or other) are necessary and yet the imminent threat of the illness may feel low, and there is the threat of acceptance erosion over time.

In conclusion: "A focus on social norms...provides an opportunity for a communication strategy in a context where other communication strategies for vaccination may feel tapped out....Creative community engagement efforts may be able to leverage positive experiences with vaccinators to help foster social norms and protect against the risk of acceptance erosion."