Immunologic Effect of Bivalent mRNA Booster in Patients Undergoing Hemodialysis

   This correspondence reports on a case series of 55 hemodialysis patients who had received four prior SARS-CoV-2 vaccinations and were monitored before and after a fifth dose of a bivalent mRNA vaccine (targeting ancestral strain and Omicron BA.4/BA.5). Anti-spike IgG concentrations rose significantly post-vaccination: by a factor of 2.5 in patients with prior Omicron breakthrough infection and by a factor of 7.3 in those without. Patients with prior infection had higher baseline and post-booster antibody levels, but those without prior infection showed substantial increases in neutralizing capacity (BA.4: ×4.9, BA.5: ×3.3) and antibody avidity (17%). Neutralization activity correlated strongly with pre-booster IgG levels and avidity, while age was not a significant factor. The findings support recommendations for periodic booster vaccination in high-risk populations lacking hybrid immunity.

   This correspondence reports on a case series of 55 hemodialysis patients who had received four prior SARS-CoV-2 vaccinations and were monitored before and after a fifth dose of a bivalent mRNA vaccine (targeting ancestral strain and Omicron BA.4/BA.5). Anti-spike IgG concentrations rose significantly post-vaccination: by a factor of 2.5 in patients with prior Omicron breakthrough infection and by a factor of 7.3 in those without. Patients with prior infection had higher baseline and post-booster antibody levels, but those without prior infection showed substantial increases in neutralizing capacity (BA.4: ×4.9, BA.5: ×3.3) and antibody avidity (17%). Neutralization activity correlated strongly with pre-booster IgG levels and avidity, while age was not a significant factor. The findings support recommendations for periodic booster vaccination in high-risk populations lacking hybrid immunity.