And after H1N1 exposure during the convalescent stage of SARS-CoV-2 infection, IL-6 cytokine levels were increased after infection and the levels were much higher in the mice on 7 dpi infected by H1N1 during the convalescent stage of SARS-CoV-2 infection than ones in the mice infected only by H1N1, and IL-6 cytokine levels were increased earlier in the mice infected by H1N1 on 7 dpi of SARS-CoV-2 infection. This evidence concerns the gene IL6 and infection.