Antibody course and memory B-cell response in the first year after SARS-CoV-2 infection

Abstract

Background

The possibility of repeat infections with SARS-CoV-2 raises questions regarding quality and longevity of the virus-induced immune response.

Methods

The antibody course and memory B-cell (MBC) response against SARS-CoV-2 proteins, influenza virus nucleoprotein (NP) and tetanus toxin (Ttx) were examined in adults with mild to moderate SARS-CoV-2 infection in the first year after infection.

Results

The concentration of SARS-CoV-2 RBD-specific antibodies was low compared with the concentration of influenza virus NP-specific antibodies. The SARS-CoV-2 RBD antibody half-life increased from 95 days in the first six months to 781 days after 9-12 months. The SARS-CoV-2 NP antibody half-life increased from 88 to 248 days. Two thirds of the subjects had SARS CoV-2-specific MBC responses 12 months after infection. SARS-CoV-2 antibody levels correlated with the MBC frequency at 12 months.

Conclusions

The low concentration of SARS-CoV-2 spike protein antibodies indicates that re-exposure to the virus or vaccination are required to use the B-cell immunity to full capacity. The existence of a robust SARS CoV-2 MBC response at 12 months in most subjects and the substantially increasing antibody half-life provide evidence that the immune response is developing into long-term immunity. The early antibody reaction and the ensuing MBC response are interdependent.