I am also highly uncertain of this. Briefly though, elderly people are more susceptible to actual infection, and I would think would be more likely to express s

I am also highly uncertain of this. Briefly though, elderly people are more susceptible to actual infection, and I would think would be more likely to express symptoms / have higher viral load. So it depends if the marginal likelihood of more symptoms = self-isolating sooner is counterbalanced by more symptoms = spread more easily for a given encounter. Anyway, ignoring the spreading part, the susceptibility alone does explain it to an extent, as you implied: > It's the ones that are most easily infected (because of their particular biology, lifestyle, etc.) who are first infected.