fever/temperature was 39.1 C; falls; her legs had given out from under her; multiple pulmonary nodules measuring up to 1.1 cm; systemic inflammatory response syndrome (SIRS); This is a literature report from the Elsevier, 2021, vol 397; pg. 1 (DOI: 10.1016/S0140-6736(21)00464-5) entitled "Fluorodeoxyglucose PET/CT findings in a systemic inflammatory response syndrome after COVID-19 vaccine".  A 65-year-old woman attended the hospital with a 1-day history of fever and falls, saying that her legs had given out from under her. The patient's symptoms began within 1 day of the first dose of the mRNA-1273 SARS-CoV-2 vaccine. She had a medical history of hypertension and diabetes. On examination in the emergency department, the patient's temperature was 39.1°C, her respiratory rate was 25 breaths per min, and her heart rate was 88 beats per min. As she met the criteria for systemic inflammatory response syndrome (SIRS), an extensive infection work-up was initiated and she was started on broad-spectrum antibiotics. Laboratory investigations found a D-dimer concentration of 5267 ng/mL, erythrocyte sedimentation rate of 69 mm/h, and a C-reactive protein concentration of 63.4 mg/L. The patient's white blood cell count, lactate, urinalysis, respiratory pathogen panel including SARS-CoV-2 and urine and blood cultures were unremarkable. Due to concerns of exposure to SARS-CoV-2, the PCR test was repeated after 24 h, but this was again negative. CT of the patient's chest showed multiple pulmonary nodules measuring up to 1.1 cm. A small filling defect in a distal subsegmental pulmonary artery was also seen, which the authors thought was inconsistent with an acute pulmonary embolism and probably artifactually. Doppler ultrasounds of the patient's lower limbs were normal; her head CT was also normal. 4 days after presentation, fluorodeoxyglucose (F-FDG) PET/CT was done to characterize the pulmonary nodules; it showed uptake in the fat stranding posterior to the right deltoid; moderately increased uptake within multiple right axillary lymph nodes; and diffusely increased splenic uptake. The pulmonary nodules had no uptake-indicating that they were probably benign. The patient's symptoms resolved 3 days after the vaccination. Given the imaging findings, the temporal relationship of the symptoms to the vaccination, and negative test results from an extensive work-up for malignant and infectious causes, the authors believe, the diagnosis was a local and systemic immune response following vaccination. However, possible masking effects of broad-spectrum antibiotics cannot be excluded. The high D-dimer concentration probably reflected significant concomitant coagulation and fibrinolysis associated with SIRS. The local response was demonstrated by hypermetabolism within the axillary lymph nodes draining the site of intramuscular injection; diffusely increased splenic activity suggests a systemic response- corroborated by elevated inflammatory markers. As the global vaccination effort continues, more patients will undoubtedly require assessment and investigation shortly after immunization. Imaging and laboratory findings consistent with a systemic immune response might result in further unnecessary evaluation or interventions. However, findings overlap with other diseases- notably those of the F-FDG PET/CT scan in patients with malignancies. Recognition of the clinical and imaging features of the systemic immune response to vaccination might become essential in the coming months.  No follow up attempts are needed. No further information is expected.; Sender's Comments: A causal association between BNT162B2 and the reported events cannot be excluded based on a compatible temporal relation. The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to RAs, Ethics Committees, and Investigators, as appropriate.