Initial unsolicited report received from the literature on 18-Mar-2017. This case was linked with 2017SA047650 (Same reporter). Background. Case reports have suggested that vaccines may trigger transverse myelitis (TM) or acute disseminated encephalomyelitis (ADEM), but the evidence for a causal association is inconclusive. We analyzed the association of immunization and subsequent development of TM or ADEM. Methods. We identified all cases of TM and ADEM in the Vaccine Safety Datalink population. Using a case-centered method, we compared vaccination of each case to vaccination of all matched persons in the study population, who received the same type of vaccine, with respect to whether or not their vaccination occurred during a predetermined exposure interval. We calculated a risk difference (excess risk) of TM and ADEM for each vaccine. Results. Following nearly 64 million vaccine doses, only 7 cases of TM and 8 cases of ADEM were vaccinated during the primary exposure window 5-28 days prior to onset. For TM, there was no statistically significant increased risk of immunization. For ADEM, there was no statistically significant increased risk following any vaccine except for Tdap (adolescent and adult tetanus, reduced diphtheria, acellular pertussis) vaccine. Based on 2 exposed cases, the odds ratio for Tdap exposure 5-28 days prior to ADEM onset was 15.8 (95% confidence interval [CI], 1.2-471.6; P = .04), and the estimated excess risk was 0.385 (95% CI, .04 to 1.16) cases per million doses. Conclusions. We found no association between TM and prior immunization. There was a possible association of ADEM with Tdap vaccine, but the excess risk is not likely to be more than 1.16 cases of ADEM per million vaccines administered. This case involves a male patient (age was not reported) who was vaccinated with a dose DIPHTHERIA, TETANUS AND ACELLULAR PERTUSSIS VACCINE (TDAP), a dose of MENINGOCOCCAL VACCINE (batch number, expiration date, dose, site and route of administration were not reported for both vaccines) on an unspecified date. Medical history and concomitant medication were not reported. On an unspecified date, following the vaccination the patient developed acute disseminated encephalomyelitis (ADEM). It was a case of an inappropriate age at vaccine administration (not recommended for his age group at that time). The lab data and corrective treatment were not reported. Outcome of the event was not reported. Upon internal review, the company decided to consider the event serious due to important medical event: Acute disseminated encephalomyelitis. Documents held by sender: none. Sender's Comments: Patient was diagnosed with Acute Disseminated Encephalomyelitis (ADEM), following TDAP VACCINE and MENINGOCOCCAL POLYSACCHARIDE VACCINE. Time to onset is compatible but additional information regarding patient detail medical history, infectious history which could trigger immune system, family history of any immune disorder, past vaccination history and its tolerance are needed to further assess the case. As patient received meningococcal vaccine at inappropriate age details regarding it are needed. Based on available information the role of vaccine cannot be assessed.