Humoral immunity to SARS-CoV-2 can be supplemented with polyclonal sera from
convalescent donors or an engineered monoclonal antibody (mAb) product. While
pentameric IgM antibodies are responsible for much of convalescent sera's neutralizing
capacity, all available mAbs are based on the monomeric IgG antibody subtype. We now
show that IgM mAbs derived from immune memory B cell receptors are potent neutralizers of
SARS-CoV-2. IgM mAbs outperformed clonally identical IgG antibodies across a range of …

The authors regret that in the original version of their article, the relative affinity graphs for
204 IgM and IgG in Fig. 2 D were accidentally reversed while preparing figures for final
publication. The remainder of the figure, including the Kd reported in the associated table, is
correct as originally published. The corrected Fig. 2 D is shown here.