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6th Edition of World Congress on Infectious Diseases

June 24-26, 2024 | Paris, France

June 24 -26, 2024 | Paris, France
Infection 2024

Seki Masafumi

Speaker at Infection Conferences - Seki Masafumi
Saitama Medical University International Medical Center, Japan
Title : Clinical features of adult, hospitalized, non-vaccinated COVID-19 patients during the omicron variant surge in Japan


Background: The mortality of SARS-CoV-2 infection in non-vaccinated patients is still thought to be high despite the appearance of the omicron subvariant. A total of 36 adult, non-vaccinated patients who were hospitalized with SARS-CoV-2 infection during the omicron variant surge were included in this study.

Case series: Severity of illness at admission was mild, moderate, and severe in 0 (0%), 29 (80.6%), and 7 (19.4%) patients, respectively, and three (3/36=9.1%) patients died. The patients who died were as follows. (Case 1) A 64-year-old man on hemodialysis developed severe pneumonia caused by SARS-CoV-2 infection. His pneumonia did not worsen, but he developed septic shock on Day 5 with a catheter-related blood stream infection due to methicillin-resistant Staphylococcus aureus (MRSA) and extended spectrum beta-lactamase (ESBL)-producing Escherichia coli. (Case 2) An 87-year-old man with a history of esophageal cancer had moderate pneumonia at admission, but suddenly developed massive brain hemorrhage on Day 6. (Case 3) A 94-year-old man with a history of brain infarction and atrial fibrillation had moderate pneumonia on admission. His pneumonia was improving, but he died on Day 7 of acute renal failure and suspected recurrent brain infarction.

Conclusions: These data and cases suggest that non-vaccinated patients showed high mortality, especially elderly male patients with underlying diseases. They died due to reasons other than respiratory failure and/or pneumonia, and impairment of blood vessels, especially in the brain, heart, and kidneys, by SARS-CoV-2 infection was thought to have occurred, though the omicron variant has generally low pathogenicity.


Professor Seki has been graduated from Department of Medicine, Nagasaki University, as Medical Doctor, with the specialties including Internal Medicine, Infectious Diseases, and Infection Control. Later on he obtained his post-graduation, started working at Osaka University. After the professor of Tohoku Medical and Pharmaceutical University, presently he has been working at the Saitama Medical University Internatinal Medical Center, Hidaka City, Saitama, Japan.