exaggerated cellulitis; painful arm; swollen arm; Upon internal review on 24-Nov-2021, case 2021SA386973 will be deleted, it is duplicate of case 2021SA380564 and all the information from the case 2021SA386973 will be merged in the case 2021SA380564.  Initial information was received on 12-Nov-2021 regarding an unsolicited valid serious case from an Other Health Professional (under reference- 00855619) and transmitted to Sanofi on 12-Nov-2021.  This case involves 50-year-old  male patient who experienced exaggerated cellulitis (Cellulitis), painful arm (Pain in extremity) and swollen arm (Peripheral swelling), after receiving DIPHTHERIA-2/TETANUS/5 AC PERTUSSIS VACCINE [ADACEL].  Medical history, medical treatment(s), vaccination(s), concomitant medications and family history were not provided.  On 09-Nov-2021, the patient received 0.5 mL (total) dose of suspect DIPHTHERIA-2/TETANUS/5 AC PERTUSSIS VACCINE [INJECTION, LIQUID (SOLUTION), 1X(once), lot C5882AA and expiry date 10-May-2023] via intramuscular route in arm for prophylactic vaccination.  A Product Technical Complaint (PTC) details: PTC number: 100175257 Batch number: C5882AA Expiry date: 10-May-2023 Sample status: Requested & Awaited Requested Start Date: 15-Nov-2021 Issue status: In Process End date: not applicable   On 09-Nov-2021, the patient developed serious exaggerated cellulitis (cellulitis), painful arm (pain in extremity) and swollen arm (Peripheral swelling) within 24 hours following the administration of DIPHTHERIA-2/TETANUS/5 AC PERTUSSIS VACCINE. The event cellulitis was assessed as medically significant.  She states that there have been 3 other incidences of this reaction this week. In all cases, the event occurred within 24 hours of administration. She states that four vaccines from this box have been administered, and all four patients developed this.They have now sequestered that lot and are holding for retrieval if desired.  Details of laboratory data were not reported.  It was not reported if the patient received any corrective treatment.  The reporter did not report causality of events with suspect.    At the time of report, the outcome of events was unknown.  Follow-up information received on 12-Nov-2021 from an Other Health Professional (under reference- 00855619).  Product Technical Complaint (PTC) details were added. Corresponding fields and narrative was updated accordingly.  Upon Internal review, it was identified that the later version was processed as non-significant despite of removing classification as "Non Valid" from the case, hence, a significant amendment performed to create a line for significant amendment in General tab and push the case through until submission.; Sender's Comments: This case involves  50-year-old male patient who experienced Cellulitis, Pain in extremity and Peripheral swelling after vaccination with ADACEL The time to onset is compatible. Further information regarding other medical history, concomitant medications, concurrent condition during vaccination, previous vaccination and tolerance, laboratory investigations excluding alternative etiologies for the reported event are needed to fully assess this case. Based upon the reported information, the role of the suspect vaccine cannot be assessed.