Is there any evidence that these “new” variants haven’t existed all along?
Have to ask Fauci. He’s the one who created them.
Yes, the new variant spreads so rapidly and more efficiently than the previous one that the new variant replaces the old one quickly. The variant currently dominating circulation is not the original. A mutation in March enabled more efficient cell entry and by April the new mutation had supplanted the old variant across the globe.
This new variant will likewise supplant the current one quickly. When a new variant appears, if it’s more effective at infecting hosts, it becomes pretty much the only one you see.