Vaccine coverage and determinants of incomplete vaccination in children aged 12–23 months in Dschang, West Region, Cameroon: a cross-sectional survey during a polio outbreak

Gianluca Russo, Alessandro Miglietta, Patrizio Pezzotti, Rodrigue Mabvouna Biguioh, Georges Bouting Mayaka, Martin Sanou Sobze, Paola Stefanelli, Vincenzo Vullo, Giovanni Rezza

Inadequate immunization coverage with increased risk of vaccine preventable diseases outbreaks remains a problem in Africa. Moreover, different factors contribute to incomplete vaccination status. This study was performed in Dschang (West Region, Cameroon), during the polio outbreak occurred in October 2013, in order to estimate the immunization coverage among children aged 12-23 months, to identify determinants for incomplete vaccination status and to assess the risk of poliovirus spread in the study population. A cross-sectional household survey was conducted in November-December 2013, using the WHO two-stage sampling design. An interviewer-administered questionnaire was used to obtain information from consenting parents of children aged 12-23 months. Vaccination coverage was assessed by vaccination card and parents' recall. Chi-square test and multilevel logistic regression model were used to identify the determinants of incomplete immunization status. Statistical significance was set at p < 0.05. Overall, 3248 households were visited and 502 children were enrolled. Complete immunization coverage was 85.9 % and 84.5 %, according to card plus parents' recall and card only, respectively. All children had received at least one routine vaccination, the OPV-3 (Oral Polio Vaccine) coverage was >90 %, and 73.4 % children completed the recommended vaccinations before 1-year of age. In the final multilevel logistic regression model, factors significantly associated with incomplete immunization status were: retention of immunization card (AOR: 7.89; 95 % CI: 1.08-57.37), lower mothers' utilization of antenatal care (ANC) services (AOR:1.25; 95 % CI: 1.07-63.75), being the ≥3(rd) born child in the family (AOR: 425.4; 95 % CI: 9.6-18,808), younger mothers' age (AOR: 49.55; 95 % CI: 1.59-1544), parents' negative attitude towards immunization (AOR: 20.2; 95 % CI: 1.46-278.9), and poorer parents' exposure to information on vaccination (AOR: 28.07; 95 % CI: 2.26-348.1). Longer distance from the vaccination centers was marginally significant (p = 0.05). Vaccination coverage was high; however, 1 out of 7 children was partially vaccinated, and 1 out of 4 did not complete timely the recommended vaccinations. In order to improve the immunization coverage, it is necessary to strengthen ANC services, and to improve parents' information and attitude towards immunization, targeting younger parents and families living far away from vaccination centers, using appropriate communication strategies. Finally, the estimated OPV-3 coverage is reassuring in relation to the ongoing polio outbreak.