A group from Rockefeller University, etc. has reported on naturally enhanced neutralizing antibodies after one year from SARS-CoV-2 infection.
https://www.biorxiv.org/content/10.1101/2021.05.07.443175v2.full
Convalescent participants who had not been vaccinated maintained most of their anti-RBD IgG titers between 6 and 12 months. Vaccination increased the anti-RBD plasma antibody levels, with IgG titers increasing by nearly 30-fold compared to unvaccinated individuals (in a figure below, Vac means vaccinated individuals).
Plasma neutralizing activity in 63 participants was measured using an HIV-1 pseudotyped with the SARS-CoV-2 spike protein. 12 months after infection, the geometric mean half-maximal neutralizing titer (NT50) for the 37 individuals that had not been vaccinated was 75, which was not significantly different from the same individuals at 6.2 months. In contrast, the vaccinated individuals showed a geometric mean NT50 of 3,684, which was nearly 50-fold greater than unvaccinated individuals.
To determine whether there was an increase in neutralization breadth over time, the neutralizing activity of the 60 antibodies was assayed against a panel of RBD mutants covering residues associated with circulating variants of concern: R346S, K417N, N440K, A475V, E484K and N501Y. Increased activity was evident against K417N, N440K, A475V, E484K and N501Y suggesting that evolution of the antibody repertoire results in acquisition of neutralization breadth over time.
