The world is confronting a new coronavirus variant, and officials have named it “omicron." A World Health Organization panel has classified it as a highly transmissible virus of concern. Its discovery in southern Africa sent a chill through much of the world as nations raced to halt air travel, markets fell sharply and scientists held emergency meetings. The overall risks of omicron are not yet known. But the 27-nation European Union and some other countries quickly suspended air travel from southern Africa and stepped up other precautions.

U.S. health officials say Merck's experimental COVID-19 pill is effective but they raised questions about its safety during pregnancy. The Food and Drug Administration posted its review Friday ahead of a public meeting next week where outside experts will debate the drug's benefits and risks. If FDA authorizes the drug it would be the first pill for U.S. patients infected with the virus. All FDA-authorized drugs currently used against coronavirus require an IV or injection. The FDA will ask its experts whether the drug's benefits outweigh its risks for various patient groups, including pregnant women.

South African scientists have identified a new version of the coronavirus this week that they say is behind a recent spike in COVID-19 infections in Gauteng, the country’s most populous province. It’s unclear from where the new variant actually arose, but it was first detected by scientists in South Africa and has also been seen in travelers to Hong Kong and Botswana. Health minister Joe Phaahla said the variant was linked to an “exponential rise” of cases in the last few days, although experts are still trying to determine if the new variant is actually responsible. The World Health Organization has convened a technical group of experts to decide whether the new variant warrants being designated a variant of interest or a variant of concern.