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During surveys, it is recommended that children immunization status should be based on immunization documents. It has been noted that in some communities, a number of children are claimed to be vaccinated but have no evidence of vaccination. This work is proposed to estimate routine immunization coverage in children based on both documented vaccination and the tracking of undocumented immunization. It was a community‑based survey targeting children aged 0‑59 months in which the immunization status of children was assessed based on vaccination documents and based on a questionnaire tracking immunization sites and period for children with undocumented vaccination. The vaccination coverage and completeness were estimated from data collected in immunization cards and re‑estimated after tracking the immunization status of children with no immunization cards. Of 1435 children reached in households, 1430 (99.7%) were included. Of 1072 children aged 12‑59 months, 194 (18.1%) received DPT‑Hi+Hb 3 with evidence and 399 (37.2%) with evidence and tracking. In the same age group, the dropout rate from DPT‑Hi+Hb 1 (157 doses administered) to DPT‑Hi+Hb 3 (127 doses administered) with evidence was 19.1% and 42.4% with evidence and tracking. The tracking of immunization status in children with no evidence of vaccination allows to determine their immunization status and to improve the reliability of the estimated vaccination coverage. This strategy could be adopted to be part of the planning and implementation of vaccination coverage surveys of EPI vaccines.

Abstract Background Monitoring of the expanded program on immunization’s performance is not only limited to routine periodic reports but equally includes surveys. Based on unpublished national EPI surveillance data from the past 5 years in Cameroon, the Foumban health district has reported a high number of vaccine preventable disease suspected cases. Contradictory information on the immunization coverage in this district exists from both administrative data and published literature. As a result, the objective of this study was to estimate the immunization coverage and dropout rate in age group 12–23 months and timeliness in age group 0–59 months among children in Foumban Health District (Cameroon), in 2018. Method This was a descriptive cross-sectional study targeting randomly selected children aged 0–59 months from Foumban health district. Data were collected by trained and supervised surveyors using a pretested questionnaire to describe the immunization coverage, timeliness and dropout rate in eighty clusters of about thirty buildings selected by stratified random sampling in July 2018. Results In total, 80 clusters covering 2121 buildings were selected and all were reached (100%). A total of 1549 (81.2%) households accepted to participate in the survey and 1430 children aged 0–59 months including 294 (20.6%) aged 12–23 months were enrolled into the study. Of these 1430 children, 427 [29.9 (27.4–32.2)%] aged 0–59 months were vaccinated with evidence. In the age group 12–23 months, the immunization coverage with evidence of BCG, DPT-Hi + Hb 3 and measles/rubella were 28.6(23.4–33.9)%, 22.8 (18.1–27.6)% and 14.3 (10.3–18.1)% respectively. Within age group 0–59 months; the proportion of children who missed their vaccination appointments increased from 23.3 to 31.7% for the vaccine planned at birth (BCG) and last vaccine planned (Measles/Rubella) for the EPI program respectively. In age group 12–23 months; the specific (DPT-Hi + Hb1–3) and general (BCG-Measles/Rubella) dropout rates of vaccination with evidence were 14.1 and 50.0% respectively. Conclusion Documented immunization coverage, dropout rate and timeliness in Foumban Health district are lower than that targeted by the Cameroon EPI. Competent health authorities have to take necessary actions to ensure the implementation of national guidelines with regards to children access to immunization. Also, studies have to be conducted to identify determinants of low immunization coverage and delays in immunization schedules as well as high dropout rates.

BackgroundCountries’ Expanded Program on Immunization (EPI) contribute to the reduction of mortality and morbidity, but access to these vaccines remains limited in most low-income countries. ObjectiveWe aim to assess whether involving community volunteers (CVs) to track children’s vaccination status and demographic movements and using recorded data to plan catch-up immunization sessions can improve children’s vaccination timeliness, completeness, and coverage. MethodsThis was a field-based randomized controlled trial and communities of the Foumban health district in West 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 assess and record in a register, details of EPI-targeted children, their demographic movements and immunization status. The scanned recorded pages were sent to the health center immunization team through WhatsApp and used to organize monthly community catch-up immunization sessions. In the control group, EPI vaccination sessions were routinely conducted. Surveys were conducted at 6 and 12 months from the beginning of the intervention in both study groups to assess and compare immunization timeliness, coverage, and completeness. ResultsOverall, 30 buildings per cluster were surveyed at midline and endline. 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. At 12 months intervention, the month one timeliness of bacille Calmette–Guerin (BCG) vaccine did not increase in the intervention group compared with the control group for the age groups 0-11 months (adjusted odds ratio [aOR] 1.1, 95% CI 0.7-1.8) and 0-59 months (aOR 1.1, 95% CI 0.9-1.4), and significantly increased 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 diphtheria-pertussis-tetanus and hepatitis B+Hemophilus influenzae type B (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. ConclusionsFindings support that involving CVs to track children’s vaccination status and demographic movements and using recorded data to plan catch-up immunization sessions improve children’s vaccination timeliness, completeness, and coverage. This strategy should be adopted to improve access to vaccination for EPI target populations and the consistency verified in other contexts. Trial RegistrationPan African Clinical Trials Registry PACTR201808527428720; https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=3548