Parental concerns and uptake of childhood vaccines in rural Tanzania – a mixed methods study

Background: Vaccine hesitancy has been recognized as an important barrier to timely vaccinations around the world, including in sub-Saharan Africa. In Tanzania, 1 in 4 children is not fully vaccinated. The objective of this mixed methods study was to describe and contextualize parental concerns towards vaccines in Tanzania. Methods: Between 2016 and 2017, we conducted a cross-sectional survey (n = 134) and four focus group discussions (FGDs, n = 38) with mothers of children under 2 years of age residing in Mtwara region in Southern Tanzania. The survey and FGDs assessed vaccination knowledge and concerns and barriers to timely vaccinations. Vaccination information was obtained from government-issued vaccination cards. Results: In the cross-sectional survey, 72% of mothers reported missed or delayed receipt of vaccines for their child. Although vaccine coverage was high, timeliness of vaccinations was lower and varied by vaccine. Rural mothers reported more vaccine-related concerns compared to urban mothers; literacy and access to information were identified as key drivers of the difference. Mothers participating in FGDs indicated high perceived risk of vaccine-preventable illnesses, but expressed concerns related to poor geographic accessibility, unreliability of services, and missed opportunities for vaccinations resulting from provider efforts to minimize vaccine wastage. Conclusions: Findings from our cross-sectional survey indicate the presence of vaccination delays and maternal concerns related to childhood vaccines in Tanzania. In FGDs, mothers raised issues related to convenience more often than issues related to vaccine confidence or complacency. Further research is necessary to understand how these issues may contribute to the emergence and persistence of vaccine hesitancy and to identify effective mitigation strategies. The methods described in this study were part of a larger study that aimed to understand barriers to timely vaccine uptake in southern Tanzania and develop a digital health intervention to promote timely vaccine uptake. The study was conducted in one urban district (Mtwara Municipality) and one rural district (Mtwara District Council) in Mtwara Region in Southeastern Tanzania. Mtwara Region has an estimated population of 1.3 million people; the two districts included in this study have an estimated population of 336,000 [19, 20]. The Tanzania Ministry of Health, Community Development, Gender, Elderly and Children and the national Immunization and Vaccine Development (IVD) program oversee the provision of routine childhood vaccinations in Mtwara Region. This study was limited to government health facilities which provide the vast majority of childhood vaccinations. In 2015–16, coverage of all basic childhood vaccines as per national guidelines (Supplementary Table 1) in Mtwara Region was estimated to be 79%, mirroring the national coverage rate of 75% [16]. The methods of the cross-sectional survey are reported below in accordance with the STROBE checklist for cross-sectional studies (Supplementary Table 2). Women ages 16 years or older, with children ages 12–23 months, were eligible to participate in the cross-sectional survey on vaccination knowledge, concerns, and practices. The minimum child age for the survey was set to 12 months to allow for the assessment of vaccine uptake in their first year of life. A priori power calculations suggested that a stratified sample of 10–12 women per facility from 12 health facilities would yield adequate statistical power (> 0.8) to characterize differences in sociodemographic characteristics between rural and urban mothers and to identify medium to strong correlates of vaccine hesitancy. Between May and June 2017, we used a combination of purposive and snowball sampling strategies to recruit mothers from 4 urban and 8 rural government health facilities and the surrounding communities for participation in the cross-sectional survey. Trained research assistants approached eligible women presenting with children to the well child clinic at participating facilities for consent and enrollment. To reduce biases from facility-based enrollment, participating women were asked to identify other potentially eligible women in their communities. Trained research assistants approached referred women in their homes for eligibility determination, consent, and enrollment. Trained research assistants conducted cross-sectional surveys with mothers at health facilities, homes, or other mutually agreed-upon locations. The survey was interviewer administered, and data were collected on a tablet device using the QualtricsXM survey platform. Vaccination knowledge and concerns were assessed using questions adapted from a WHO survey on vaccine hesitancy [21], and a prior study (see Acknowledgements). Other survey questions assessed women’s sociodemographic characteristics, reproductive history, and barriers to vaccinations. Children’s vaccination histories in their first year of life, including dates of vaccinations, were obtained from government-issued vaccination cards. The key outcomes of interest, mothers’ vaccine hesitancy and the timeliness of children’s vaccinations, were measured as follows: Survey data were analyzed using Stata v.15 (StataCorp LLC). Distributions of the key outcomes of interest, sociodemographic characteristics of mothers, and other correlates of vaccine hesitancy and vaccination decisions, were described using means and ranges for continuous variables and proportions for categorical variables. Variation in these characteristics between rural and urban mothers were analyzed using Student’s t-tests and chi-squared tests for continuous and categorical variables, respectively. Associations between sociodemographic characteristics, vaccine hesitancy, and vaccine coverage and timeliness were assessed using linear least squares regression models that accounted for clustering at the level of the referral, i.e., each index woman enrolled from a health facility and her community-based referrals formed a cluster. Observations with missing data were excluded from the respective analyses. Women ages 16 years or older, with children ages 0–23 months, were eligible to participate in focus group discussions (FGDs) on barriers to childhood vaccination. As is typical of qualitative analyses, the goal was to identify community norms and common themes across groups. Given broad eligibility criteria we did not anticipate significant differences between participants across groups; groups were expected to be similar except for their geographic location. Due to these considerations and published reports on qualitative sample size considerations [22–24], we determined a priori that four FGDs with 10 women per FGD would likely be sufficient to reach saturation. Between December 2016 and February 2017, a purposive sampling approach was used to recruit mothers from two urban and two rural government health facilities for participation in FGDs. Trained research assistants approached eligible women for consent and enrollment. Two female Tanzanian research assistants (RAs) trained in qualitative data collection conducted four FGDs with mothers using a semi-structured guide aimed at understanding locally and socio-culturally relevant barriers to timely vaccinations. FGD domains consisted of open-ended questions with probes on the role of women in vaccination decision-making, and barriers to vaccine uptake. Each FGD included approximately 10 participants and lasted between 40 and 60 min. FGDs were audio-recorded, transcribed in Swahili, and translated into English for analysis. A short survey captured basic demographic information of FGD participants; field notes were written after the FGDs by the RAs. Owing to logistical considerations and variations in English literacy, transcripts were not returned to participants for comments. Translated FGD transcripts were uploaded into QSR NVivo v.11, and thematic analyses were conducted utilizing four interrelated steps: reading, coding, data display, and data reduction. Within FGDs, participants organically discussed issues related to vaccine hesitancy. To summarize and synthesize those discussions, transcripts were coded by the first author using a codebook made of a priori, structural codes based on the “3 Cs” model of vaccine hesitancy, comprising convenience, complacency, and confidence, with an eye towards identifying community norms on these issues (see Supplementary Table 4) [25]. Narrative summaries were created for each of the “3 Cs” domains and are presented below with accompanying quotes from the mothers for illustration. The narrative summaries were routinely shared with the study team and feedback was incorporated.