Persistent covid-19 infection; This literature-non-study case was reported in a literature article and describes the occurrence of COVID-19 (Persistent covid-19 infection) in a 48-year-old female patient who received mRNA-1273 (Spikevax) for COVID-19 prophylaxis.   Concurrent medical conditions included Castleman's disease.   On an unknown date, the patient received first dose of mRNA-1273 (Spikevax) (unknown route) 1 dosage form. On an unknown date, the patient experienced COVID-19 (Persistent covid-19 infection) (seriousness criteria hospitalization and medically significant). The patient was treated with REMDESIVIR at an unspecified dose and frequency and TOCILIZUMAB at an unspecified dose and frequency. At the time of the report, COVID-19 (Persistent covid-19 infection) had not resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Blood fibrinogen: On second hospitalization, severely elevated. On an unknown date, C-reactive protein: On second hospitalization, severely elevated. On an unknown date, Chest X-ray: radiograph revealed bilateral infiltrates. On an unknown date, Fibrin degradation products: On second hospitalization, severely elevated. On an unknown date, Inflammatory marker test: On second hospitalization, severely elevated. On an unknown date, SARS-CoV-2 test: (Positive) On first hospitalization, positive, (Positive) On discharge, PCR testing for SARS-CoV-2 was positive on multiple occasions and (Positive) On second hospitalization, positive.   The action taken with mRNA-1273 (Spikevax) (Unknown) was unknown.   For mRNA-1273 (Spikevax) (Unknown), the reporter did not provide any causality assessments.   A 48-year-old, female with a known Castleman's disease and no concomitant medications,  presented with shortness of breath at the ED. She received one dose of mRNA-1273 vaccine, and 6 months later, was admitted for COVID-19 and hypoxemia. Reportedly, she contracted COVID-19 prior to her 2nd dose. In-patient treatments included systemic glucocorticoids and remdesivir. She was discharged home on supplemental oxygen via nasal cannula at 2 L/min. Over the next 2 months, her respiratory status declined with dyspnea and hypoxemia leading to ED consultation and eventual ICU admission. COVID-19 PCR tests returned positive on multiple occasions, including her 2nd hospitalization. Inflammatory markers including fibrin degradation products, CRP, and fibrinogen were severely elevated, whilst chest radiograph showed bilateral infiltrates. High flow oxygen, remdesivir, systemic glucocorticoids, and tocilizumab were administered. Continuous decline of her condition prompted mechanical ventilation use. Transfer to another institution for evaluation of extracorporeal membrane oxygenation was done.  The authors postulated the proclivity of CD to cytokine excess had a synergistic effect on the inflammatory components of COVID-19 infection in this patient as she remained symptomatic for 6 months with progressive worsening.  Company Comment: This literature non-study case concerns a 48-year-old, female patient with a known Castleman's disease, who experienced an unexpected, medically significant event of Persistent COVID-19 after receiving one dose of mRNA-1273 vaccine that led to hospitalization. Reportedly, she contracted COVID-19 prior to the second dose. After 6 months from her 1st vaccination, she presented with shortness of breath at the emergency department and was subsequently admitted for COVID-19 and hypoxemia. Systemic glucocorticoids and remdesivir were given, which improved her condition. She was sent home with supplemental oxygen via nasal cannula at 2 L/min. Over the next 2 months, her respiratory status declined with dyspnea and hypoxemia leading to ED consultation and eventual ICU admission. Multiple positive COVID-19 PCR tests were obtained. Inflammatory markers including fibrin degradation products, C-reactive protein, and fibrinogen were severely elevated. Chest radiograph revealed bilateral infiltrates. Treatments included high flow oxygen, systemic glucocorticoids, remdesivir, and tocilizumab. Continuous decline of the patient's condition prompted mechanical ventilation. Transfer to another institution for evaluation of extracorporeal membrane oxygenation was done. The authors postulated cytokine excess from CD had synergistic effect on the inflammatory components of COVID-19 infection in this patient as she remained symptomatic for 6 months with progressive worsening. Case is confounded by Castleman's disease. The benefit-risk relationship of mRNA- 1273 vaccine is not affected by this report. Event's seriousness assessed per medical judgement.; Sender's Comments: This literature non-study case concerns a 48-year-old, female patient with a known Castleman's disease, who experienced an unexpected, medically significant event of Persistent COVID-19 after receiving one dose of mRNA-1273 vaccine that led to hospitalization. Reportedly, she contracted COVID-19 prior to the second dose. After 6 months from her 1st vaccination, she presented with shortness of breath at the emergency department and was subsequently admitted for COVID-19 and hypoxemia. Systemic glucocorticoids and remdesivir were given, which improved her condition. She was sent home with supplemental oxygen via nasal cannula at 2 L/min. Over the next 2 months, her respiratory status declined with dyspnea and hypoxemia leading to ED consultation and eventual ICU admission. Multiple positive COVID-19 PCR tests were obtained. Inflammatory markers including fibrin degradation products, C-reactive protein, and fibrinogen were severely elevated. Chest radiograph revealed bilateral infiltrates. Treatments included high flow oxygen, systemic glucocorticoids, remdesivir, and tocilizumab. Continuous decline of the patient's condition prompted mechanical ventilation. Transfer to another institution for evaluation of extracorporeal membrane oxygenation was done. The authors postulated cytokine excess from CD had synergistic effect on the inflammatory components of COVID-19 infection in this patient as she remained symptomatic for 6 months with progressive worsening. Case is confounded by Castleman's disease. The benefit-risk relationship of mRNA- 1273 vaccine is not affected by this report. Event's seriousness assessed per medical judgement.