[jbeam]

Exponential growth. Lets say that there is one delta infection and one omicron infection in the population. Each delta infection causes two more people to be infected, while each omicron infection causes three more people to be infected.

The growth of a single delta infection: 1 -> 2 -> 4 -> 8 -> 16 -> 32 -> 64

Versus a single omicron infection: 1 -> 3 -> 9 -> 27 -> 81 -> 243 -> 729

Omicron started out as 50% of the cases and over 6 reinfection cycles became 90% of the cases. Delta just can't keep up. These are made up numbers but that is the general idea.

[callumprentice]

Nod - that explains why omicron grew so quickly but why, in doing so, does delta not persist?

[nostromo]

To actually answer the question: because immunity from one transfers to the other.

Omicron is basically a self-administering vaccine that is preventing Delta from spreading as easily.

[whatshisface]

It does persist, all else remaining the same, but since it is so much less infectious it will go extinct if and when anything makes a dent in Omicron. Dents including lockdowns, increased vaccination, changes in public behavior or eventual immunity.

[convolvatron]

i assume that the immunity you get from having O helps damp down cases of D