Neutralizing antibody responses and cellular responses against SARS-CoV-2 Omicron subvariant BA.5 after mRNA SARS-CoV-2 vaccination in kidney transplant recipients

Abstract

Although the mRNA SARS-CoV-2 vaccine has improved the mortality rate in the general population, its efficacy against rapidly mutating virus strains, especially in kidney transplant recipients, remains unclear. We examined the anti-SARS-CoV-2 spike protein IgG antibody and neutralizing antibody titers and cellular immunity against B.1.1, BA.1, and BA.5 antigens in 73 uninfected kidney recipients and 17 uninfected healthy controls who received three doses of an mRNA SARS-CoV-2 vaccine. The IgG antibody titers were significantly lower in recipients than in healthy controls. Similarly, neutralizing antibody titers against three viral variants were significantly lower in recipients. When the virus was mutated, the neutralizing antibody titers decreased significantly in both groups. In cellular immunity analysis, the number of spike-specific CD8 + non-naïve T cells against three variants significantly decreased in recipients. Conversely, the frequency of spike-specific Th2 CD4 + T-cells in recipients was higher than that in healthy controls. Twenty recipients and seven healthy controls also received a bivalent omicron-containing booster vaccine, leading to increased IgG and neutralizing antibody titers in both groups. However, the increase was significantly lower in recipients. Recipients did not gain sufficient immunity with a third dose of vaccine, indicating a need to explore methods other than vaccines.