More on cross-reactive T-cell immunity.

They found that of the SARS-CoV-2 and “common cold” coronavirus fragments that were most similar (at least 67% genetic similarity) 57% showed cross-reactivity by memory T cells.

The evidence for pre-existing T-cell immunity against Covid-19 keeps piling up, hence the case for a much lower threshold for herd immunity becomes stronger. Conversely, the case for a vaccine becomes way weaker.