At the beginning of this year, the extremely contagious BA.1 variant (also known as the omicron variant) set an astonishing record: scientists believed it was likely the most contagious virus ever, surpassing even measles.
That is, until BA.2 — or "stealth" omicron, as it has been called — came along. Studies suggest that BA.2 is between 30 and 50 percent even more contagious than its predecessor, which was already more contagious than measles.
