DW News and Documentary offers a timely analysis (15 min), “How Dangerous Is South Africa’s Coronoavirus Variant?"
Penny Moore, Wits University, is interviewed in depth. Younger people are getting it probably because of behaviors and the way the virus is reported. The AstraZeneca vaccine was not found to be very effective in stopping mild disease from this variant in young people, but it hasn’t been studied in old people to see if it stops serious disease. It is similar to Johnson and Johnson, which does.
There is also discussion of whether coronaviruses normally become milder as they evolve over a long time. They may. The four common cold viruses are mild because children are exposed to them early in life and develop deep cellular immunity to prevent serious damage.
Wikipedia embed of South Floral area, click for attribution.