RESUMEN
Supplementary immunization activities campaigns provide children with an additional dose of vaccine and deliver other interventions. However, there is dearth of information on knowledge, attitude and perception of mothers of under-five towards vaccination during supplementary immunization activities. A descriptive cross-sectional study which employed multistage sampling technique was designed to fill this gap. Four wards were randomly selected from eleven wards in Ibadan North-West Local Government Area and houses were enumerated from the selected wards, systematic random sampling was used to select houses and then respondents. A semi-structured interviewer administered questionnaire was used to elicit information on three hundred and five respondents. Knowledge scores of ≤4, 5-8, and ≥ 9 were rated poor, fair and good, respectively. Attitude scores of ≤5 and >5 was rated negative and positive attitude, respectively while perception scores ≤4 and >4 were rated negative and positive perception, respectively. Data was analyzed with SPSS version 25 using descriptive statistics and Chi-square test at 5% level of significance. The mean age of respondents was 30.6±6.1years, the highest level of education for most (68.5%) was secondary school. Their mean parity and number of under-five were 2.5±1.4 and 1.2±0.4, respectively. Knowledge was generally poor, more than half (53.1%) had poor knowledge, majority (88.2%) have positive attitude while 84.6% have a positive perception. One-fourth (24.6%) and one-fifth are of the opinion that frequent vaccination will make the vaccine ineffective and overload immune system, respectively. There was generally poor knowledge of supplementary immunizations and mothers need to be educated on the importance.