Humoral Immune Responses in German Dialysis Patients after mRNA Omicron JN.1 Vaccination

To assess the effect of the updated mRNA JN.1 omicron vaccine (bretovameran, BioNTech/Pfizer, Mainz, Germany) in an immunocompromised and elderly population, we measured humoral immune responses after mRNA omicron JN.1 vaccination in 37 haemodialysis patients before and 21 days after vaccination. We observed a 3-fold change in anti-S IgG, and a 4·7-fold change in anti-S omicron IgG. Memory B cells (MBC) exclusively binding the receptor binding domain (RBD) of JN.1 displayed a median frequency of 0·11% before vaccination and changed significantly 3·9-fold to a median of 0·43%. Cross reactive JN.1 RBD and Wuhan-Hu-1 S-binding MBCs and MBCs only binding to Wuhan-Hu-1 S changed 2·3-fold and 1·8-fold, respectively. Using a vesicular stomatitis virus-based pseudovirus particle (pp) neutralisation assay, baseline response rates were 86% for XBB.1.5 pp , 78% for JN.1 pp , 73% for and KP.2 pp , 65% for KP.2.3 pp and KP.3 pp , and 68% for LB.1 pp . After vaccination, the response rates for all pseudoviruses increased significantly, and we observed a mean increase in neutralisation of XBB.1.5 pp , JN.1 pp , KP.2 pp , KP.2.3 pp , KP.3 pp , and LB.1 pp of 8·3-fold, 18·7-fold, 22·5-fold, 18·7-fold, 25·5-fold, and 23·5-fold, respectively. In summary, our report provides first evidence for a firm humoral immune response in dialysis patients after mRNA omicron JN.1 vaccination. Our data suggest that the vaccine could be highly effective at enhancing protection of vulnerable populations against evolving SARS-CoV-2 variants.