Tracking Demographic Movements and Immunization Status to Improve Children's Access to Immunization: Field-Based Randomized Controlled Trial

"This strategy should be adopted to improve access to vaccination for EPI target populations and the consistency verified in other contexts."

In Cameroon, many children are not vaccinated on time or do not complete their vaccination schedule as required by the national Expanded Program on Immunization (EPI), despite the fact that the EPI vaccination calendar is posted at almost all health facilities in the country. During previous EPI supervision activities, this group of researchers observed that many children and pregnant women miss out on vaccinations during scheduled periods because of short- or long-term travel. The aim of this project is to test whether engaging community volunteers (CVs) to record vaccination status and demographic movements of children at the household level and to plan immunisation sessions for missed children can improve EPI vaccination timeliness, completeness, and coverage.

This field-based randomised controlled trial (RCT) allocated communities of the Foumban health district in West Cameroon to control or intervention groups. In the control group, EPI vaccination sessions were routinely conducted. In the intervention group, one CV per community was trained to visit households monthly for a year to assess and record in a register the details of EPI-relevant children, their demographic movements, and their immunisation status. The immunisation team sent the scanned recorded pages to the health centre through WhatsApp and used the data to organise monthly community catch-up immunisation sessions. These sessions were conducted with the full participation of the CVs, who chose an accessible vaccination site in the community and informed parents with children needing vaccinations about the session.

For the RCT, 30 buildings per cluster were surveyed at midline (6 months) and endline 12 months) of the intervention. Of the 633 and 729 visited households in the intervention group at midline and endline, 630 (99.5%) and 718 (98.4%), respectively, consented to participate. In the control group, 507 and 651 households were visited and 505 (99.6%) and 636 (97.7%), respectively, consented to participate. The primary data collected included the immunisation status and time of the administration of the Bacille Calmette-Guerin (BCG), polio zero, diphtheria-pertussis-tetanus and doses 1-3 of the hepatitis B+Hemophilus influenzae type B (DPT-Hi + HB) vaccines, as well as sociodemographic characteristics. Selected findings:

• At 12 months intervention, the month one timeliness of BCG vaccine increased, though not significantly, in the intervention group compared with the control group for the age groups 0-11 months (adjusted odds ratio [aOR] 1.1, 95% confidence interval [CI] 0.7-1.8) and 0-59 months (aOR 1.1, 95% CI 0.9-1.4). (One potential reason: To prevent vaccination wastage, most vaccination teams had decided not to open the BCG vial when fewer than 15 children in need were present at a vaccination session, which this delayed the vaccination schedule.) However, the timeliness did significantly increase for the first-year BCG vaccine administration for the age group 0-23 months (aOR 1.5, 95% CI 1.1-2.2).
• The coverage of DPT-Hi +Hb dose 3 (aOR 2.0, 95% CI 1.5-2.7) and of DPT-Hi+Hb dose 1 (aOR 1.8, 95% CI 1.4-2.4) vaccines increased significantly in the intervention group compared with the control group in the age groups 12-59 months and 12-23 months, respectively.
• Specific (DPT-Hi+Hb dose 1 to DPT-Hi+Hb dose 3: aOR 1.9, 95% CI 1.4-2.6) and general (BCG to measles: aOR 1.5, 95% CI 1.1-2.1) vaccine completeness increased significantly in the intervention group compared with the control group.

Reflecting on the findings, the researchers note that the intervention tested in this study combines several approaches tested in previous studies - e.g., reaching out to parents (by SMS (short messaging service)/text messages or telephone calls), home visits, and training - and "innovates by involving CVs in the assessment of immunization status and using 2 immunization coverage-monitoring registers, one of which is used by the community to update children's immunization status, with the updated pages scanned and sent using WhatsApp to the health facility to update the health facility-based register for planning of immunization sessions."

Furthermore, the intervention is grounded in communication and collaboration among households, CVs, and vaccination teams to organise catch-up vaccination sessions, a strategy that can help promote sustainability because the intervention "is locally organized at a lower cost, it is accepted by the different actors involved in vaccination campaigns, and is therefore expected to be easily scalable across contexts." It is CVs - hailing from, living in, and speaking the local language of the community - who engage in communication with parents and caregivers to convince them to bring children to the community-organised vaccination sessions.

In short, the intervention "makes it possible to determine the number of EPI-targeted children living in each community each month, identify those needing each of the EPI vaccinations, use this information to communicate with parents and vaccination teams, and organize immunization sessions at locations and on dates chosen by the community and thus more accessible to the children's guardians....In addition..., the intervention contributed to improving the timeliness because it included repeated household visits to monitor the progress of children's vaccination status and ensured that they received all doses of the recommended vaccines."

Based on the findings, the researchers conclude: "Given that the intervention significantly improved children's access to BCG vaccination before the end of their first year of life,...it can be recommended in similar contexts as this study and evaluated in other contexts with the hope of using it to improve children's timely access to BCG vaccination in other contexts in need."