Acute Eosinophilic Pneumonia; hypoxia worsened; cough productive; pink tinged sputum; exertional shortness of breath; Chills; fever; profuse pulmonary nodules; scattered ground glass opacities/Diffuse bilateral reticulonodular and alveolar opacities; septal thickening; Tachycardia; Tachypnea; This case was reported in a literature article and described the occurrence of eosinophilic pneumonia acute in a 64-year-old male patient who received DTPa (Reduced antigen) (dTpa vaccine) for prophylaxis.   Concurrent medical conditions included hyperlipidemia and nonsmoker (lifelong non-smoker). Concomitant products included atorvastatin.   On an unknown date, the patient received dTpa vaccine. On an unknown date, several hours after receiving dTpa vaccine, the patient experienced eosinophilic pneumonia acute (serious criteria GSK medically significant), hypoxia (serious criteria GSK medically significant), productive cough, sputum discolored, exertional dyspnea, chills, fever, lung nodule, lung opacity, pulmonary septal thickening, tachycardia and tachypnea. The patient was treated with ceftriaxone, azithromycin, glucocorticoids nos (Glucocorticoids) and oxygen. On an unknown date, the outcome of the eosinophilic pneumonia acute, hypoxia, productive cough, sputum discolored, exertional dyspnea, chills, fever, lung nodule, lung opacity, pulmonary septal thickening, tachycardia and tachypnea were recovering/resolving.   The reporter considered the eosinophilic pneumonia acute, hypoxia, productive cough, sputum discolored, exertional dyspnea, chills, fever, lung nodule, lung opacity, pulmonary septal thickening, tachycardia and tachypnea to be possibly related to dTpa vaccine.     Additional Information: GSK Receipt Date: 13-JUL-2022 Author Comment: A 64-year-old male with history of hyperlipidemia on atorvastatin presented to the emergency room with complaints of cough productive of pink tinged sputum, exertional shortness of breath, chills and fever with maximum recorded temperature of 101-degree fahrenheit. His symptoms started within a few hours of receiving tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine two days before the emergency room visit. He denied any recent travel. He was a lifelong non-smoker and was employed as hospital case manager. His vitals were significant for tachycardia 116/min, tachypnea 30 breaths/min and SaO2 of 93 % on 10L. On physical examination, he was noted to have coarse and diminished breath sounds in both lung fields. Initial lab work showed elevated leukocyte count of 20.4 k/uL with absolute eosinophil count of 1.6 k/uL. Other labs were unremarkable. Diffuse bilateral reticulonodular and alveolar opacities were visualized on chest X-ray. Computed tomography (CT) of the chest showed profuse pulmonary nodules, scattered ground glass opacities and septal thickening concerning for bilateral multifocal pneumonia. Blood cultures and sputum cultures were obtained, and he was empirically treated with ceftriaxone and azithromycin. Sputum eosinophil smear was positive raising concerns for fungal and parasitic infections. Cultures remained negative and his hypoxia worsened. Thus, infectious diseases and pulmonology were consulted. Extensive infective disease work-up for bacterial, fungal, parasitic and viral pathogens came back negative. CT guided biopsy of a lung nodule demonstrated interalveolar eosinophil and fibrin deposition consistent with eosinophilic pneumonia. Patient was started on glucocorticoids with dramatic improvement in his symptoms, imaging and oxygen needs. With his symptom onset following Tdap vaccine and negative infective work-up, Acute eosinophilic pneumonia (AEP) was suspected to be triggered by the vaccine.  This was the first report of AEP following Tdap vaccine in adults. Only up to 30% of patients with AEP will have peripheral eosinophilia. Diagnosis is usually confirmed on lung biopsy and patients respond very well to glucocorticoids.