The Mechanism of Immune Responses to Antibodies

In a new study, people who have already been vaccinated against SARS-CoV-2 don't get a broader response to the Amacron subvariance. The researchers say they think it's because there are not enough naive B cells in the body to accommodate the new antigen. But if you just give them a vaccine just with Amacron in it, then that does amplify those antibodies. It doesn't make a lot of logical sense but I don't know what its mechanism is.