Tracking demographic movements and immunization status to improve children access to immunization (TDM-IAI): A Field-Based Randomized Controlled Trial (Preprint)

Abstract

Vaccines offered by countries’ expanded program on immunization contribute to the reduction of mortality and morbidity, but access to these vaccines remains quite limited in most developing countries.

The present trial assesses whether involving Community Volunteers (CV) to track children vaccination status and demographic movements and using recorded data to plan catch-up immunization sessions can improve children vaccination timeliness, completeness and coverage.

Methods: This was a randomized controlled field trial in which communities of the Foumban Health district based in West region of Cameroon were allocated to intervention or control groups. In the intervention group, a CV per community was trained to visit households monthly for a year to record EPI targeted children in a Community EPI register (CER), their demographic movements and assess their immunization status. CER recorded page was snapped and sent to health center immunization team through WhatsApp to be used to plan and implement monthly community catch up immunization sessions. In the control group, the EPI immunization sessions were conducted as routinely. Surveys were conducted at 6 (midline) and 12 (end line) months from the beginning of the intervention in both study groups to assess and compare immunization timeliness, coverage and completeness.

Thirty-two clusters per study group of about 160 buildings were followed for a year. In each cluster, a sample of 30 building was selected and surveyed at midline and endline. Of 633 and 729 opened households (HH) that were reached for surveys in midline and end line in the intervention groups, 99.5% and 98.4% consented to participate respectively whereas in the control group, 507 and 651 opened HH were reached and 99.6% and 97.7% consented in midline and endline surveys respectively. One year after the implementation of the intervention, the timeliness of BCG administration in the first month of life did not increase in the intervention group compared to the control group for the age groups 0-11 (adjOR = 1.1 (0.7-1.8)) and 0-59 months (AdjOR=1.1(0.9-1.4)); meanwhile the increase was significant for the first year BCG administration for the age group 0-23 months (adjusted (AdjOR= 1.5 (1.1-2.2)). The coverage of DPT-Hi+Hb3 (AdjOR= 2.0 (1.5-2.7)), DPT-Hi+Hb1(adjOR= 1.8 (1.4-2.4)) significantly increased in the intervention group compared to the control group in age groups 12-59 and 12-23 months. Specific (DPT-Hi+Hb1 to DPT-Hi+Hb3) (AdjOR= 1.9 (1.4-2.6)) and general (BCG to measles) (AdjOR=1.5 (1.1-2.1)) vaccine completeness increased significantly in the intervention group compared to the control group.

Results of the present trial support that involving CV to track children vaccination status and demographic movements and using recorded data to plan catch-up immunization sessions improve children vaccination timeliness, completeness and coverage. If its consistency is verified in other contexts, this strategy should be adopted to improve access to vaccination for EPI target populations.

Pan African Clinical Trials Registry ID: PACTR201808527428720; Approved and registered on August 22, 2018.