Is this the NEJM preliminary report referenced in the article? https://www.nejm.org/doi/full/10.1056/NEJMc2102179

Both the full panel of mutations in S and a subset of mutations affecting the receptor-binding domain (RBD) region of the B.1.1.7 variant had no significant effect on neutralization by serum obtained from participants who had received the mRNA-1273 vaccine in the phase 1 trial (Figure 1A and 1B). In contrast, we observed a decrease in titers of neutralizing antibodies against the B.1.351 variant and a subset of its mutations affecting the RBD. In serum samples obtained 1 week after the participants received the second dose of vaccine, we detected reductions by a factor of 2.7 in titers of neutralizing antibodies against the partial panel of mutations and by a factor of 6.4 against the full panel of mutations.