Effective contagion is already strongly selected for without our help.
No. What’s selected for is reproductive fitness, not contagion. Contagion is often, but not always, fit.
To what extent, and how much, is debated but the optimal virulence is not going to be 100% fatality rates; there can be cases where that happens (a new mutation accidentally makes it too virulent and the hosts are wiped out or shrunk to a nonviable population before it can evolve to something nicer, or it crosses into a new species where its carefully modulated virulence turns out to be ultra-virulent, like invasive species suddenly arriving at an isolated island) but that is not selected for. (For an interesting discussion on virulence and immune systems, see “The Acquired Immune System: A Vantage from Beneath”, Hedrick 2004 (excerpts).)
So, you can’t make a strong evolutionary argument that pandemics must be very difficult to engineer.
No. What’s selected for is reproductive fitness, not contagion. Contagion is often, but not always, fit.
To what extent, and how much, is debated but the optimal virulence is not going to be 100% fatality rates; there can be cases where that happens (a new mutation accidentally makes it too virulent and the hosts are wiped out or shrunk to a nonviable population before it can evolve to something nicer, or it crosses into a new species where its carefully modulated virulence turns out to be ultra-virulent, like invasive species suddenly arriving at an isolated island) but that is not selected for. (For an interesting discussion on virulence and immune systems, see “The Acquired Immune System: A Vantage from Beneath”, Hedrick 2004 (excerpts).)
So, you can’t make a strong evolutionary argument that pandemics must be very difficult to engineer.