Similarly, with the higher expression of ACE2 in Calu3 cells, viral release in the supernatant of Calu3/hACE2 cells infected with Omicron strain was higher than that of Delta at day five post-infection (Fig. 4), compared to Calu3 cells where Omicron has shown to have less viral particle release than Delta at 2 days post-infection [23, 25]. The gene discussed is ACE2; the disease is infection.