From the article, "A few months ago, I started a magazine assignment to answer some questions about SARS-CoV-2 and the immune system. I encountered paragraphs like this"... and the author links to this this [1] New Yorker article about COVID that was published November 2020. So from context clues, was probably published in late 2020.

[1] https://www.newyorker.com/magazine/2020/11/09/how-the-corona...