COVID-19: “Cautious optimism” from NIH and BMJ on T cells and immunity

Since May, I’ve closely followed research on T cell cross-reactivity to SARS-CoV-2 in unexposed individuals. This could hint at some degree of pre-existing immunity that’s potentially more widespread than previously believed, leading to a number of hopeful possibilities: Could herd immunity thresholds be lower than believed? Are seroprevalence studies underestimating the number of people infected…