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Immune cells against earlier Sars-CoV-2 variants also recognize Omikron well and can thus protect against severe disease / Vaccination can improve immune response even after infection / Study published in Nature Microbiology

The Omikron variant of SARS-CoV-2 has caused another major wave of infections worldwide. This is because even people who have been vaccinated or who have been infected with a previous variant of the virus can become infected with Omikron. Nevertheless, severe cases are relatively rare. Scientists at the Medical Center - University of Freiburg have now broken down in detail how the cross-variant protection against infection or severe disease progression arises. The researchers published their findings in the online edition of the renowned journal Nature Microbiology on April 28, 2022.

"In our study, we were able to show that memory T cells that were formed after vaccination or infection with an earlier Sars-CoV-2 variant can also recognize the Omikron variant very well and protect against a severe course of infection," explains co-study leader Dr. Maike Hofmann, who heads a research group at the Department of Medicine II at the Medical Center - University of Freiburg. Hofmann will be awarded the Heinz Maier-Leibnitz Prize of the German Research Foundation for her research next week. "The antibodies' ability to bind to the Omikron variant is greatly reduced. Therefore, even after a vaccination booster, they only protect against infection with the omicron variant for a very short time," Hofmann continues.

Immune response differs in vaccinated and recovered individuals

The scientists also investigated possible differences in the immune responses of recovered and vaccinated individuals. "Both groups have a broad T cell response: in recovered individuals, the T cells recognize several viral proteins. In vaccinated individuals, the immune response is essentially directed against the spike protein, which is produced from the mRNA vaccine in the body and then triggers the immune response. The T-cell response against the spike protein is broader and stronger in vaccinated patients than in recovered patients," reports co-study leader Prof. Dr. Christoph Neumann-Haefelin, Head of the Gerok Liver Center at the Medical Center - University of Freiburg. "If convalescents are vaccinated, the T-cell responses are also more diverse, which increases protection against severe disease progression in future infections," says Neumann-Haefelin.

Two of the first authors of this work are the two young physicians Dr. Julia Lang-Meli and Dr. Hendrik Luxenburger. They are supported by the "Clinician Scientist" program IMM-PACT at the Medical Center - University of Freiburg, which is funded by the German Research Foundation. It allows young physicians to be released from their duties for research. "These important results have only been possible thanks to the close networking of clinical and research work," emphasizes Prof. Dr. Robert Thimme, Medical Director of the Department of Medicine II at the Medical Center - University of Freiburg.

"In the public perception, the immune response against SARS-CoV-2 is often reduced to the formation of antibodies. The study now published makes a significant contribution to obtaining a more complete picture of immune protection in connection with Sars-CoV-2," says Prof. Dr. Lutz Hein, Dean of the Faculty of Medicine - University of Freiburg.

Original title of the study: SARS-CoV-2-specific T-cell epitope repertoire in convalescent and mRNA-vaccinated individuals
DOI: 10.1038/s41564-022-01106-y
Link to the study: https://www.nature.com/articles/s41564-022-01106-y

Picture caption: Analysis of the COVID-19-specific immune response in the research laboratory
Image source: Medical Center - University of Freiburg

Contact:
Prof. Dr. Christoph Neumann-Haefelin
Head of Gerok Liver Center
Department of Medicine II (Focus: Gastroenterology, Hepatology, Endocrinology and Infectiology)
Medical Center - University of Freiburg
Phone: 0761 270-32800
christoph.neumann-haefelin@uniklinik-freiburg.de