A composition contains at least one fucosylated oligosaccharide, for use in preventing and/or treating a URT infection in an infant or young child fulfilling at least one of the following criteria: i) the infant or young child is born from a non-secretor mother and/or is fed with a mother's milk deficient in at least one fucosylated oligosaccharide, ii) the infant or young child has at least one sibling, and iii) the infant or young child was born by C-section.
