Omicron BA.1 virus infection in vaccinated patients remodels immune memory

Alberto Domingo Lopez-Munoz, Laboratory of Viral Diseases, NIAID/NIH Teams from the internal medicine department of the Henri-Mondor AP-HP hospital, the Institut Necker - Enfants Malades, the Mondor Institute for Biomedical Research, the Institut Pasteur, Inserm, and the Paris-Est Créteil University studied immune memory after infection with the Omicron BA.1 variant in patients vaccinated with three doses of the messenger RNA COVID-19 vaccine. The results of this study ( MEMO-VOC) , coordinated by Dr Pascal Chappert and Pr Matthieu Mahévas, in collaboration with Dr Immunity review. The Spike protein of SARS-CoV-2 ¹ Omicron BA.1 carries 32 mutations compared to the ancestral strain (Hu-1) originally identified. These mutations significantly alter neutralizing antibodies induced by natural SARS-CoV-2 infection and/or vaccination with an encoding mRNA vaccine. Immune memory is a mechanism that protects individuals against reinfection. This defense strategy of the body, which is the basis of the success of vaccines, includes the production of protective antibodies in the blood (detected by serology) as well as the formation of memory cells (memory B lymphocytes 2 ), ^capable of quickly reactivate into antibody-producing cells upon re-infection. The scientific literature has already shown ^3,4 that the repertoire of memory B cells generated by two or three doses of mRNA vaccines contains neutralizing clones against all variants of SARS-CoV-2 up to Omicron BA.