“…In studies that compared a cohort of children with CD to a control group, a significant difference in the response to HBV vaccination was constantly found between the two groups [ 12 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ] ( Table 1 ). Wanting to clarify if age was a risk factor, Filippelli et al [ 35 ], by comparing the percentage of responders and non-responders among three age groups (0–5.5 years, 5.5–9.5 years and 9.5–17 years), found no significant differences between the youngest and the oldest group. The data on adult patients also confirmed the high failure rate of HBV vaccination in CD subjects [ 38 , 39 , 40 ].…”