A 68 year old white male received an injection of MassBiologics' Td vaccine (Lot #A097A) on July 13, 2017 intramuscularly in his left deltoid as a routine booster during a visit to establish with a new physician. No other vaccines were administered during this visit nor within the 4 months prior to the visit. Later that same day as Td administration (7/13/2017), the patient was admitted to the Medical Center. The primary reporter communicated that the hospital records stated that the patient was experiencing unresponsive episodes or questionable seizures. The patient has multiple chronic health conditions which include: coronary artery disease requiring bypass surgery, recurrent cerebrovascular accidents or transient ischemic attacks, benign prostatic hyperplasia, hyperlipidemia, neuropathy, gastroesophageal reflux disease, chronic renal insufficiency, fever blisters, and gout. He was taking his routine daily medications at the time of immunization: ECOTRIN (eight 81mg tablets), PLAVIX (75mg), NEURONTIN (300mg, 4x a day), PROTONIX (40mg, 2x a day), CRESTOR (10mg), FLOMAX (0.4mg), and a multivitamin with iron (9mg per 400microgram tablet). In addition, the following medications are prescribed on an "as needed" basis and are not believed to have been taken at the time of immunization: VALIUM, VALTREX, and NITROSTAT. It was noted that the patient has allergies to clindamycin, LEVAQUIN, LIPITOR, simvastatin, and sulfa drugs. The primary reporter, an RN and Clinical Manager at the outpatient provider's facility, provided details on the treatment given and tests performed from the hospital's electronic medical records. Treatment consisted of giving the patient anticonvulsants; initially KEPPRA was given via IV but the patient was later switched to DEPAKOTE during hospitalization. The patient's workup included multiple lab tests, an EEG, imaging by CT, an ultrasound, and an MRI; no information was provided on the exact dates or results of these tests. The medical record noted that no seizures were reported since the morning of July 15, 2017, although no information was provided to confirm if seizure activity was witnessed in the hospital ("transient neurological symptoms" were noted in the hospital records). The patient was discharged from the hospital on July 17, 2017, after a 4-day hospitalization. A nurse from the outpatient provider's office spoke with the patient on the phone on July 18, 2017. No new reactions or updates on the patient's condition were recorded during this call. The primary reporter contacted MassBiologics later that same day to inquire whether there was any information available on seizures following Td administration. On July 19, 2017, MassBiologics called the patient's physician to confirm details on the patient's medical history and Td immunization event and to obtain additional information about the adverse event. She was not able to provide any details regarding the adverse event, noting that she was not present during hospitalization and did not witness the adverse event. She mentioned that she scheduled a follow-up visit with the patient to occur on July 25, 2017 and agreed to follow-up with MassBiologics after that date. Follow up on July 27, 2017: The patient's physician called MassBiologics to follow up on the patient's recovery status after his visit with her on July 25. The physician confirmed that there were no other reactions to report for this event, and that the patient had no further seizure-like activity or unresponsive episodes since the morning of July 15. The patient saw a neurologist (date unknown) and is currently completing his prescription of DEPAKOTE. The neurologist plans to perform another EEG after the patient completes his course of DEPAKOTE for 1 week and 1 day. The patient's physician indicated that the EEG performed during hospitalization showed no signs of seizure, but that he was on DEPAKOTE at the time. The physician considers the patient's recovery status as ongoing until the neurology follow-up. Sender's Comments: All of the adverse events presented in this case were assessed as serious due to the patient requiring hospitalization. Seizures would be considered a labeled reaction because the term "convulsions" (which is often used synonymously with seizures) is listed in Td's package insert and the onset of the adverse event was within several hours of vaccine administration. However, the patient does have a past history of multiple cerebrovascular events so it is unknown whether the possible seizure activity is related to his underlying medical problems or the receipt of Td. Unresponsive episodes are assessed an unexpected, although it is possible that they could be a consequence of seizure activity. MassBiologics plans to follow up with the patient's physician after the results of his second EEG are available. This report will be updated with any additional information received.