> COVID is becoming more deadly over time because there is a selective pressure towards more transmissibility. More transmissibility can increase the severity of illness if the virus more readily replicates or more easy infects human cells.
I read that as talking about infection fatality rate (IFR). I'm not aware of any evidence that covid's IFR is increasing.
It seems that the Alpha variant is more virulent than the original, but it's hard to measure virulence to a high degree of confidence.
IFR is not quite the right thing to measure, we are interested in differences in mortality due to mutation of the virus, but there are many confounding variables in the quality of treatment and populations that get infected to remove. e.g. if a virus stayed exactly static you would expect mortality to decrease over time as better treatments are found.
Citation needed.