Based on nine prospective studies that assessed CMV infection in all study subjects, the rate of CMV infection ranged from 0 to 36% with the median rate of 25% [7, 8, [10] [11] [12] [13] [14] [15] [16] . The specimens used to assess CMV infection included blood, urine, and respiratory secretions. All the studies used blood to assess CMV infection. Blood was used solely in four studies [7, 11, 12, 15] , whereas urine and respiratory specimen in addition to blood samples were used in two [13, 16] and four studies [8, 10, 14, 16] , respectively. The rate of CMV infection was reported separately based on the type of specimens in these studies (Table 1 ). Considering only studies that assessed for viremia, the CMV infection rate ranged from 0 to 33% with the median rate of 20%. Thereafter, we reported the rate of CMV infection diagnosed based on the presence of viremia.