There are already reports of (vaccinated) young people getting seriously ill.
Unlike with other viruses, there is little selective pressure towards being less deadly, because illness/death mostly happen after transmission.
And while I'm not a virologist, it doesn't seem far-fetched that "breeds higher viral loads more quickly" would be correlated not only with transmissivity, but also with "kills more".
There are already reports of (vaccinated) young people getting seriously ill.
Unlike with other viruses, there is little selective pressure towards being less deadly, because illness/death mostly happen after transmission.
And while I'm not a virologist, it doesn't seem far-fetched that "breeds higher viral loads more quickly" would be correlated not only with transmissivity, but also with "kills more".