Something else I thought about cat, is what Geert Vanden Bossche has been saying. He predicted younger and younger people will be affected in subsequent waves, mostly due to their sitting on suboptimal antibodies from a previous asymptomatic or barely symptomatic infection. He says it suppresses their innate immunity for a time, which is not spike specific but also less able to bind and neutralize the virus, neutralizing it, being the key to sequestration and control of the virus. That, coupled with the increased viral loads leading to quicker clotting and desaturation, could be the reasons.