According to Professor Peter Fleming of the Royal Hospital for Children in Bristol, United Kingdom, cot death--also known as sudden infant death syndrome (SIDS)--is not caused by vaccinating infants against pertussis, tetanus, and diphtheria. Fleming, who was commenting on a new study he reported in the British Medical Journal, noted that an anti-vaccination group had raised concerns about the possible link between SIDS and the shots. Suspicions about a possible connection grew after the age at which babies were immunized was reduced in 1990, making the shots coincide with the peak age for SIDS. In his research, however, Fleming found that those infants who were immunized were at a lower risk of dying than infants who were not.