Markets plunged on Friday, hope of taming the coronavirus dimmed and a new term entered the pandemic lexicon: Omicron.
The Covid-19 variant that emerged in South Africa was named after the 15th letter of the Greek alphabet.
The naming system, announced by the World Health Organization in May, makes public communication about variants easier and less confusing, the agency and experts said.
For example, the variant that emerged in India is not popularly known as B.1.617.2. Rather, it is known as Delta, the fourth letter of the Greek alphabet.
There are now seven “variants of interest” or “variants of concern” and they each have a Greek letter, according to a W.H.O. tracking page.
Some other variants with Greek letters do not reach those classification levels, and the W.H.O. also skipped two letters just before Omicron — “Nu” and “Xi” — leading to speculation about whether “Xi” was avoided in deference to the Chinese president, Xi Jinping.