Mostly because the virus evolves, it’s global, and various countries have differing containment strategies and vaccination capacity. Again, it evolves so whatev

Mostly because the virus evolves, it’s global, and various countries have differing containment strategies and vaccination capacity. Again, it evolves so whatever the most successful variant is will take root in areas which have poor containment and evolve again. Unless we can contain it and vaccinate against the latest variants globally and all at once, it will likely persist in some form or another. Here's a good article on viral escape: https://www.washingtonpost.com/nation/interactive/2021/vaccination-pace-herd-immunity/ https://www.washingtonpost.com/nation/interactive/2021/vacci...