The initial literature search yielded 3,644 unique articles. Of these, 23 studies comprising 13,833 patients were included in this review. The study dates ranged from 1982 to 2017 and ranged in size from 78 to 2,829 patients. Two studies included preverbal children only, 10 included preverbal children aged 5 years and younger, 2 studies included children aged 6 years or younger, and 9 studies included a broad range of children from preverbal to adolescence. Eight of the 23 studies were conducted in North America, whereas the remaining 15 studies were conducted outside of North America. The overall rate of pneumonia was 19% in North American studies and 37% in studies conducted outside of North America.