[AntiImperialis2]

The strains being transmitted the most are likely to keep the host the most healthy for the longest time.

However, this is only true in the LONG RUN, when different variants have played out for a while.

In the short term, there could be a highly transimissible strain with a much higher mortality. It will eventually come to a point when the most common strains in a population are milder strains... but one of the reasons that happens is that hosts with immune systems unable to handle the strain die off... and those who survive do so because they can handle it better. So, at a later stage, it looks like the virus got milder, but:

- it doesn't generally apply to all strains

- the strains look mild later because only those for whom it was mild survive

[jnxx]

Exactly. There exists a really good example for that, the Spanish flu pandemic of 1918.