Clinical Manifestation, Management, and Outcomes in Patients with COVID-19 Vaccine-Induced Acute Encephalitis: Two Case Reports and a Literature Review.

INTRODUCTION: Vaccination is one of the best strategies to control coronavirus disease 2019 (COVID-19), and multiple vaccines have been introduced. A variety of neurological adverse effects have been noted after the implementation of large-scale vaccination programs. METHODS: We reported two rare cases of possible mRNA-1273 vaccine-induced acute encephalitis, including clinical manifestations, laboratory characteristics, and management. RESULTS: The clinical manifestations might be related to hyperproduction of systemic and cerebrospinal fluid (CSF) cytokines. mRNA vaccines are comprised of nucleoside-modified severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA, which is translated into SARS-CoV-2 spike protein by the host's ribosomes, activating the adaptive immune response. Exposed mRNA or vaccine components may also be detected as antigens, further resulting in aberrant proinflammatory cytokine cascades and activation of immune signaling pathways. Both patients exhibited significant clinical improvement after a course of steroid therapy. CONCLUSIONS: The use of COVID-19 vaccines to prevent and control SARS-CoV-2 infections and complications is the most practicable policy worldwide. However, inaccurate diagnosis or other diagnostic delays in cases of vaccine-induced acute encephalitis may have devastating and potentially life-threatening consequences for patients. Early diagnosis and timely treatment can result in a favorable prognosis.

The role of anti-platelet factor 4 antibodies and platelet activation tests in patients with vaccine-induced immune thrombotic thrombocytopenia: Brief report on a comparison of the laboratory diagnosis and literature review.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel human pathogen causing coronavirus disease 2019 (COVID-19). Rare cases of COVID-19 vaccine-induced immune thrombotic thrombocytopenia (VITT) after the ChAdOx1 nCoV-19 (AstraZeneca) vaccination have been reported. We performed a test for anti-heparin/ platelet factor 4 (PF4) antibodies and functional assay using flow cytometry. METHOD: A healthy woman presented to the emergency department with chest pain, headache, and abdominal pain after the first vaccination with AstraZeneca. Polymerase chain reaction (PCR) test for SARS-CoV-2 was negative. Chest computed tomography (CT) showed pulmonary artery embolism and brain magnetic resonance imaging (MRI) revealed cerebral sinus-venous thrombosis. Abdominal CT demonstrated the thrombosis with occlusion in her right hepatic vein. Laboratory studies revealed decreased platelet counts, and high D-dimer level. Finally, laboratory results indicated high PF4 antibodies level high and a positive platelet activation test, confirming the diagnosis of VITT. RESULTS: Treatments including intravenous immunoglobulin, methylprednisolone and direct oral anticoagulant were administered. The results of a follow-up platelet count and D-dimer were normal. In addition, the titer of PF4 antibodies (optical density: 0.425; normal ≤ 0.4, enzyme-linked immunosorbent assay) fell. After a 3-month follow-up, her general condition improved gradually. CONCLUSIONS: The use of COVID-19 vaccines to prevent SARS-CoV-2 infections and complications is considered the most practicable policy for controlling the COVID-19 pandemic and is being forcefully pursued in the global area. Appropriate laboratory diagnosis facilitates the accurate and rapid diagnosis. Early recognizing and appropriate strategies for VITT are required and can provide these patients with more favorable patient outcomes. This report also elected to make comparisons of clinical manifestation, laboratory diagnosis, and management in patients with VITT.