Fig. 8.

Overall infection and mortality given emerging strains with different transmissibility and severity. When the severity of the emerging strain is kept unchanged, the infection and mortality are positively correlated with transmissibility; given the same transmissibility, the infection will almost always rise as the severity decreases, while the mortality rises first and then decreases. The artificially drawn white dashed line is a possible evolutionary trajectory of the virus towards a higher infection rate (a) and a rising and then decreasing mortality rate (b)