Tailoring Immunization Programmes: Using Patient File Data to Explore Vaccination Uptake and Associated Factors

"[C]omprehensive action, investment and prioritization from decision-makers are immediately necessary for the FBiH to ensure the protection of the population against vaccine-preventable diseases."

Vaccination uptake in the Federation of Bosnia and Herzegovina (FBiH) has been declining in recent years. Measles outbreaks in the FBiH occurred in 2014-2015 and 2019, and the European Regional Certification Commission for Poliomyelitis Eradication concluded that the FBiH, due to its low population immunity, remains at high risk of sustained polio outbreak following importation. In light of the dearth of evidence-based data on the reasons for the suboptimal vaccination uptake in the FBiH, the Institute for Public Health of the FBiH decided to initiate a WHO Tailoring Immunization Programmes (TIP) project (see Related Summaries, below, for more on the approach) to understand barriers and drivers to childhood vaccination.

This was a cross-sectional study, based on primary health care (PHC) facility patient files of children, which included data about their caregivers. It included 1,800 children in 2 cohorts of children: those born in 2015 (aged 24-35 months at the time of data analysis) and 2016 (aged 12-23 months at the time of data analysis) because of the change in pertussis vaccine that occurred at this time. A structured paper-based form was developed, pre-tested, and completed by a paediatrician/nurse from the selected PHCs. Selected findings:

• Coverage was lower for all vaccines for urban residences compared to rural, and vaccination occurred later in urban than rural settings for measles, mumps, and rubella (MMR1).
• Just 2% (95% confidence interval (CI) 1-3%) had received no vaccinations at all. A total of 8% (95% CI 4-11%) were unvaccinated except for Bacillus Calmette-Guérin (BCG) and Hepatitis B (HepB1).
• The drop-out rate for HepB from first to third dose was 34% (95% CI 27-41%); for diphtheria, tetanus, and pertussis (DTP), the rate was 26% (95% CI 19-33%).
• Looking at children born in 2016, the odds of being fully vaccinated were 3 times (95% CI 1.6-5.4) higher for a child living in a rural area compared to an urban area. Conversely, a child of Roma community affiliation was less likely to be fully vaccinated than a non-Roma child (although this is based on a small sample).
• Among children born in 2015, the odds of being vaccinated with MMR1 were 4.7 times (95% CI 2.6-8.2) higher for a child living in a rural area compared to an urban area and 1.4 times higher (95% CI 1.1-1.8) if the mother is older compared to younger (over 35 years to 30-35 years).

Prior to conducting this study, there were a number of assumptions in the FBiH about factors related to vaccination - some of which were confirmed, and others challenged, by the study findings. There was an assumption that anti-vaccination sentiment prevails among caregivers in the FBiH. This notion is challenged by the high coverage for birth doses and vaccines given at 1 and 2 months of age. Instead, the study identified challenges related to the completion of the vaccination schedule and timeliness. For all assessed vaccines, the study confirmed considerable delays and drop-out. Insight from these authors' qualitative studies with caregivers (unpublished data) and health workers reveal that reasons for these delays and drop-outs include: changes in the immunisation schedule, lack of knowledge and/or information about the importance of completing the schedule, lack of encouragement from health workers to return for vaccination, inefficient or absent reminders, poorer doctor-patient relationships in urban compared to rural settings, and competing priorities for caregivers in urban settings.

Another assumption was that caregivers have particular concerns about the MMR vaccine due to misperceived risks of potential side effects. The researchers report that anti-MMR vaccine information is increasingly circulating in the Balkan countries (sharing similar languages), and MMR vaccination rates in these countries have declined more significantly than other vaccines. The current study confirmed that one-third of eligible children had not received MMR vaccination, higher than for any other vaccines. Specifically, MMR1 vaccine compared to DTP1 vaccine was less accepted (65% versus 86%) and more delayed (4 months versus 2 months).

The findings may inform efforts to increase vaccine uptake in the FBiH. Suggestions include:

• Ensure a stable supply of mandatory vaccines to avoid vaccine shortages and consequential adjustment of the immunisation calendar.
• Educate health workers and caregivers to improve knowledge related to safety concerns.
• Improve urban vaccination settings in order to encourage urban caregivers to bring children for vaccination.
• Support Roma families to bring children for vaccination.
• Digitalise the vaccination reporting system to ensure accurate coverage estimates.