Understanding Drivers of Vaccine Hesitancy among Pregnant Women in Nigeria: A Longitudinal Study

"Adapting the [5C] scale to predict vaccination intention and behavior in Nigeria was novel and revealing."

Parents - mothers, in particular - can strongly influence childhood vaccination decisions. There is a likelihood that a mother's hesitation could affect childhood vaccination. However, little is known about vaccine hesitancy among pregnant women in Nigeria. This study's aims are to adapt the 5C psychological antecedence scale for the Nigerian context and to measure predictors of intention to vaccinate among pregnant women (prenatal) and subsequent vaccination behaviour (postnatal) using two independent measurement points from the same participants.

The 5C model focuses on confidence in vaccines and the system that delivers them; complacency (not perceiving diseases as high risk), constraints (structural and psychological barriers), calculation (engagement in extensive information searching), and aspects pertaining to collective responsibility (willingness to protect others). This study used an adapted 5C model with three additional variables: religion, masculinity (the extent of the influence of fathers or husbands on childhood vaccination decisions in households), and vaccination-related rumour (hereafter, 5C+).

Measurement point one, prenatal (T1), used a structured questionnaire using the 5C+ scale to predict the vaccination intention of pregnant women. Measurement point two, postnatal (T2), was conducted 12 months postnatal to assess if intention (prenatal) translated into actual vaccination behaviour. It is expected that the 5C will predict vaccination intention and behaviour. At T1, 255 pregnant women participated in the study. At T2, 96 of those same women (representing 38%) were surveyed.

The most significant vaccination information sources are during antenatal care activities organised routinely at the hospitals by healthcare workers and during a consultation with doctors at 50.4% (T1) and 28.6% (T2). Also, healthcare workers conducting antenatal care activities and doctors were the two most trusted sources for vaccination information by pregnant women at 87% and 82%, respectively.

At T1, for all subscales of the original 5C, the internal consistency indicators were too low for all five indicators as compared to reliability indicators obtained in Western samples. Because the items did not fit well with their intended constructs in Nigeria, the 15 items of the 5C scale could not be aggregated. Instead, subsequent analyses were performed using the single items, including the extensions religion, masculinity, and rumour (5C+).

Analysis was performed to determine the demographic and psychological variables related to routine vaccination intention at T1. Muslims indicated lower vaccination intentions compared to Christian participants. Vaccination intentions increased with confidence in the public authorities/health system but decreased if participants indicated that their husband's approval was important for vaccination and if they believed in the rumour that vaccination causes infertility.

At T2, vaccination behaviour measurement instruments were the same as at T1, except that the main dependent variable was actual vaccination behaviour that had taken place until T2, i.e., vaccines received by children within the period and corresponding to routine immunisation recommendations. The results revealed that vaccination was more likely when it followed mothers' religious beliefs, when confidence in vaccine effectiveness was high, and when mothers felt responsible for the collective (collective responsibility). Conversely, a higher level of everyday stress (constraint) was related to less vaccination behaviour. Surprisingly, prenatal vaccination intentions (T1) did not play a role in actual vaccination behaviour. (Perhaps, "during pregnancy, vaccination is not a priority or a relevant issue, rather the decision about such an important undertaking is undecided at prenatal. I.e., the search for information or knowledge for vaccination decision-making takes place later when the child is born.")

Reflecting on the findings, the researchers note that the measurement of the psychological antecedent of confidence seems to be the strongest predictor of the 5C scale, especially the item that measures confidence in the public authority/health system. The study shows that participants' confidence in the country's healthcare system is related with a more positive intention to vaccinate their child in the future. Generally, there is declining confidence in Nigeria's public authority/health system, which helps explain why Nigeria remains the country with both the highest under- and unvaccinated children in the world (2018 data).

The confidence-eroding factor in the public authority or health system here could also be linked to misconceptions about the preventive role of immunisation in Nigeria, especially where uptake rates are very low. Studies found that some healthcare workers and health system managers make exaggerations about immunisation to motivate uptake, thereby giving caregivers the false impression that immunisation prevents all childhood diseases. Hence, the inability of immunisation to prevent all diseases erodes trust and confidence in the public institutions managing immunisation and eventually leads to loss of faith in immunisation as an intervention to give protection.

Also, the source of information and communication is critical to people's perception of vaccination. Based on this study, mothers who received their vaccination information through the antenatal care services/healthcare workers and doctors are confident about vaccine efficacy and are more likely to have a positive attitude toward vaccination and a higher intention to vaccinate their children. Therefore, more should be done to link antenatal care services to all primary healthcare facilities in communities to enhance knowledge sharing, thereby increasing vaccination demand.

Religion significantly influences decision-making in many parts of sub-Saharan Africa (SSA), so the confirmation of religion as a determinant of childhood vaccination intention among mothers was not surprising. In particular, regions with strong Islamic influence (e.g., the Muslim-dominated northern region) have lower immunisation coverage and high vaccine hesitancy, adding to other variables such as low literacy levels. Hence, a religiously tailored and targeted intervention approach is suggested. Since trust in vaccination information from antenatal care was highest, Nigeria's immunisation stakeholders could integrate religious talks on vaccine acceptance into their activities. Also, enlisting the support of influential Muslim women's organisations such as the Federation of Muslim Women Association of Nigeria (FOMWAN) could be a wise strategy.

In several communities in the SSA, a strong patriarchal culture subsists. Therefore, the child's father or husband's opinion is crucial in overall household vaccination decision-making. Strengthening fathers' trust in and approval of vaccination will likely support the willingness of mothers to protect their children's health by vaccinating them.

Also, since the study revealed that mothers who possess higher education were related to stronger beliefs in vaccination effectiveness and collective responsibility, mothers of infants with lower education should be reached through vaccination literacy campaigns.

In short, this study found that, although vaccination intention was not meaningfully related to actual behaviour, vaccination was related to three of the 5Cs: when confidence in the vaccine effectiveness was high (confidence), when mothers felt responsible for collective well-being (collective responsibility), and when mothers indicated lower levels of everyday stress (constraint). Likewise, additional variables (5C+) played a role in vaccination behaviour. Among the lessons to be gleaned from the 5C+ analysis: Rumour and/or misinformation was a very powerful influencing factor among all four predictors of vaccination behaviour and, thus, should be addressed with effective rebuttal strategies.

The researchers conclude that further studies are still necessary to align a suitable scale for measuring vaccine hesitancy in the SSA sub-region and Nigeria in particular. There is a need to increase empirical studies that glean behavioural insights surrounding vaccine hesitancy in SSA - especially those that focus specifically on pregnant women's childhood vaccination decision-making procesess. Future studies might consider emergence of a new scale for measuring vaccine hesitancy based on confidence, constraints, collective responsibility, religion, masculinity, and rumour.