Since introduction of rotavirus vaccine in the United States in 2006, five cases (four in the United States and one in Australia) of vaccine-acquired rotavirus infection in RV5-vaccinated infants with SCID have been reported in the literature.6- 8 Two additional U.S. cases of vaccine-acquired infection in RV5-vaccinated infants with SCID and one case of vaccine-acquired infection in an RV1-vaccinated infant with SCID from outside the United States have been reported to the Vaccine Adverse Event Reporting System (VAERS). The eight infants (four males and four females) were diagnosed with SCID between ages 3 months and 9 months and had received 1-3 doses of rotavirus vaccine before the diagnosis. All the infants had diarrhea, and most had additional infections (e.g., Pneumocystis jirovecii, rhinovirus, adenovirus, Salmonella,Escherichia coli, and Giardia) at the time of SCID diagnosis. Rotavirus infection was diagnosed by enzyme immunoassay in seven of the eight patients for whom this information was available. In all eight cases, vaccine-acquired rotavirus infection was confirmed by reverse transcription–polymerase chain reaction (RT-PCR) and nucleotide sequencing. Prolonged shedding of vaccine virus was documented in at least six of these cases, with duration of up to 11 months.