“…The Vaccine Confidence Index (VCI) was used in Brazil [ 51 ], involving 952 parents, of whom 352 were parents of children under 5 years of age. Out of the 32 countries examined in the study [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 ], 21 studies were carried out in countries categorized as high-income by the World Bank, 11 studies in upper-middle-income countries, 9 studies in lower-middle-income countries, and 1 study in a low-income country, specifically Ethiopia. Table 2 provides an overview of the characteristics of all the studies included in the meta-analysis.…”