Vaccine Hesitancy and Trust in Sub-Saharan Africa

"...individuals' trust in the government and society are key predictors of vaccine hesitancy."

Vaccine hesitancy is primarily a trust issue. Systematic and literature reviews have documented a negative relationship between trust in institutions that are involved in the production, supply, distribution, and monitoring of vaccines and vaccine hesitancy. Existing research on the trust-vaccine hesitancy nexus has focused heavily on COVID‑19 vaccination, with the majority of studies examining industrialised countries. Looking at sub-Saharan Africa (SSA), this multi-country study investigated the influence of trust in five distinct types of institutions (government, media, science, pharmaceutical companies, and society) on vaccine hesitancy for vaccines related to polio and human papillomavirus (HPV), which it benchmarks against the COVID‑19 vaccine.

The study sample comprised 5,203 individuals living in six SSA countries (Ghana, Kenya, Nigeria, South Africa, Tanzania, and Uganda). The selection of vaccines studied was based on the countries' national strategies to integrate the following vaccines into their (standard) immunisation programmes: polio (novel oral polio vaccine type 2, or nOPV2, which is used only for polio outbreak response); HPV (Garasil-4 and Cervarix, the use of which is currently small in low- and middle-income countries); and COVID-19 (Comiranty, which is still in the process to be approved in most African countries as of this writing).

A majority of respondents stated they were vaccinated against polio (89.74%) and COVID-19 (71.42%), while a minority said they received any vaccination against HPV (about 10%). About 9% of the sample were classified as vaccine hesitant. Vaccine hesitancy differed substantially across countries and ranged from 8.3% in Kenya to 17.15% in South Africa.

Employing linear probability models, the researchers estimated by ordinary least squares (OLS) how individuals' level of trust affects vaccine hesitancy. The adopted regression framework controlled for a number of individual and country-specific characteristics as well as vaccine type.

The results suggested that individuals' level of trust in the government, in pharmaceutical firms, and in society are strong predictors of vaccine hesitancy. These coefficients were negative and statistically significant at the 95% confidence level. This means that persons with lower levels of trust in the national government, pharmaceutical companies, and society were more likely to be vaccine hesitant. The estimated coefficient on governmental trust was about twice as large as the one for societal trust and trust in pharmaceutical firms. A one-standard-deviation-higher level of trust in the government reduced the likelihood of being vaccine hesitant by around five percentage points. Levels of trust in the national media and science appeared unrelated to vaccine hesitancy.

Regarding other variables included in the regression framework, the researchers found that being female and vaccination status were negatively correlated with vaccine hesitancy (statistically significant at the 90% level).

Furthermore, the study demonstrated that these relationships are remarkably stable across vaccine, disease, and country contexts. The same trust factors that were responsible for vaccine hesitancy against COVID-19 helped explain vaccine hesitancy against other vaccines and diseases (HPV, polio). Moreover, the trust-related drivers of vaccine hesitancy were highly comparable across all six study countries. Notably, while COVID-19 and HPV are viruses that were circulating in all countries, not all countries in the study sample had recently experienced a polio outbreak. Moreover, the polio vaccine nOPV2 is distinct from the other two types of vaccines, as it is only used in emergencies and not part of the routine immunisation programmes. This situation might cause a bias of the estimates related to polio if survey participants found it hard to imagine the hypothetical case of a polio outbreak in their country. To see in how far the results are sensitive to such a situation, the researchers distinguished between countries that experienced a polio outbreak in the last few years and others. In both samples, they found a negative correlation between trust in the government and vaccine hesitancy. They also found a negative correlation between trust in the society and vaccine hesitancy, but only for the sample of countries that have experienced a polio outbreak.

These results corroborate previous literature documenting that low levels of trust in the government is a pivotal predictor of vaccine hesitancy. In contrast to several other studies, the researchers found no robust evidence for a relationship between trust in media and science on vaccine hesitancy. Moreover, they provided new evidence on how trust in society in regards to social norms influences vaccine hesitancy. The inclusion of trust in society specified as social norm could be an explanation for the null findings of trust in media and science, if those factors are mainly operating through the societal channel.

Several policy conclusions can be derived on basis of this study:

1. The results imply a rather universal relationship between trust in the government and vaccine hesitancy, enabling the use of more targeted policies to address this specific trust issue.
2. When new vaccines enter the market, raised mistrust in pharmaceutical firms can decrease vaccination uptake.
3. To increase vaccination acceptance, policymakers should focus on emphasising the social acceptance of vaccination.