The World Health Organization on Friday declared the recently-discovered B.1.1.529 strain of Covid-19, first detected in southern Africa, to be a variant of concern and renamed it Omicron. The classification puts Omicron into the most-troubling category of Covid-19 variants, along with the globally-dominant Delta, plus its weaker rivals Alpha, Beta and Gamma. Nations rushed to ban flights to slow the spread of Omicron on Friday, while stock markets and oil prices plunged on fears […]