Adenovirus-related illness; upper respiratory symptoms; suspected bronchitis; respiratory failure; sinusitis; bronchiolitis obliterans; organizing pneumonia; viral encephalitis following Adenovirus-related illness; unconscious; tonic-clonic seizures; Initial information received on 31-Aug-2022 by a healthcare professional regarding an unsolicited valid serious case issued via literature article:   This case involves a 21-year-old male patient who experienced adenovirus-related illness (Adenovirus infection) and viral encephalitis following adenovirus-related illness (Encephalitis viral) while receiving vaccine meningococcal vaccine (latency: few weeks).  The patient's past family history was not provided. A healthy patient arrived at program on May 19, 2000. His medical history was negative for underlying illnesses. He took no medications and denied alcohol or tobacco use.    In 2000 within one week of arrival, the patient received a dose of suspect meningococcal vaccine produced by unknown manufacturer lot number not reported via unknown route in unknown administration site. The patient also received several standard vaccinations.  In 2020, Jun 20-23, few weeks later, patient presented to medical clinic with upper respiratory symptoms (Respiratory symptom). His clinical evaluations did not suggest severe illness, and two bacterial throat cultures were negative. On June 23, he was prescribed a 5-day course of azithromycin for suspected bronchitis (Bronchitis). On June 24, he was found unconscious (Loss of consciousness) in the building. He was transported to a local hospital where he had tonic clonic seizures (Generalised tonic-clonic seizure) and respiratory failure that required a ventilator. A chest radiograph revealed a right upper lobe infiltrate, and computer tomography of the head was positive for sinusitis. Examination of cerebrospinal fluid revealed elevated protein levels, but no identifiable pathogens. Blood cultures were negative. He was treated with broad-spectrum antibacterial agents (i.e., vancomycin, ceftriaxone, and metronidazole) and antivirals (i.e., acyclovir and foscarnet). He did not regain consciousness and he died on July 3 from complications of encephalitis. Autopsy findings included histologic changes in the brain and spinal cord consistent with viral encephalitis. Both lungs showed bronchiolitis obliterans (Obliterative bronchiolitis) and organizing pneumonia. Cultures, special stains, and electron microscopy of autopsy specimens did not identify specific pathogens. Molecular testing by polymerase chain reaction (PCR) assay of lung and brain tissue was positive for adenovirus DNA using multiple primer sets. Analysis of premorbid and postmortem serum specimens showed a greater than fourfold rise in neutralizing antibody titers to both adenovirus types 4 and 7.  Action taken: not applicable. Corrective treatment: azithromycin, vancomycin, ceftriaxone, and metronidazole for Adenovirus infection; acyclovir and foscarnet for Viral encephalitis. Outcome: fatal for both the events.  Seriousness criteria: death, medically significant and hospitalization for both the events.  Reporter causality: related for both the events. Based upon the reported information, the role of a vaccine cannot be assessed.; Sender's Comments: Sanofi company comment dated 05-Sep-2022: This case involves a 21-year-old male patient who experienced adenovirus-related illness and viral encephalitis following adenovirus-related illness while receiving vaccine meningococcal vaccine. The causal role of drug cannot be denied for the events, but the lack of information regarding dosing details, past medications and family history precludes a comprehensive assessment in this case.; Reported Cause(s) of Death: Adenovirus-related illness