Inhibitory KIR and NKG2A receptors have been found to be upregulated during COVID-19 and likely contribute to NK cell exhaustion (205, 206) NKG2A is also highly upregulated in acute, severe COVID-19 patients, while mild and moderate patients show a recovery of NKG2A after resolution of the infection (198). This evidence concerns the gene KIR3DL1 and infection.