Viruses are programmed to mutate and variants are bound to emerge. So is the case with the SARs-COV-2 virus. Since the onset of the novel coronavirus in early 2020 up until now, new COVID-19 variants have cropped up time and again.

from Times of India https://timesofindia.indiatimes.com/life-style/health-fitness/health-news/delmicron-versus-omicron-what-should-you-be-more-scared-of-signs-to-watch-out-for/photostory/88615370.cms