Derek Thompson for The Atlantic has a followup on that recent uh-oh of a COVID-19 immunity study.

First, our immune system is a mysterious place, and the KCL study looked at only one part of it. When a new pathogen enters the body, our adaptive immune system calls up a team of B cells, which produce antibodies, and T cells. To oversimplify a bit, the B cells’ antibodies intercept and bind to invading molecules, and the killer T cells seek and destroy infected cells. Evaluating an immune response without accounting for T cells is like inventorying a national air force but leaving out the bomber jets. And, in the case of COVID-19, those bomber jets could make the biggest difference. A growing collection of evidence suggests that T cells provide the strongest and longest-lasting immunity to COVID-19—but this study didn’t measure them at all.

So, the study likely remains an important piece of answering the immunity question, but only partially addresses what our immune system does.