WHO designates new variant of concern named Omicron

The discovery of a new coronavirus variant sent a chill through much of the world Friday as nations raced to halt air travel, markets fell sharply and scientists held emergency meetings to weigh the exact risks, which were largely unknown.

A World Health Organization panel named the variant "omicron" and classified it as a highly transmissible virus of concern, the same category that includes the delta variant, the world's most prevalent. The panel said early evidence suggests an increased risk of reinfection.

In response, the United States joined the European Union and several other countries in instituting travel restrictions on visitors from southern Africa.

The White House said the U.S. will restrict travel from South Africa and seven other countries in the region beginning Monday. It did not give details except to say the restrictions will not apply to returning U.S. citizens or permanent residents, who will continue to be required to test negative before their travel.

Medical experts, including the WHO, warned against any overreaction before the variant that originated in southern Africa was better understood. But a jittery world feared the worst nearly two years after COVID-19 emerged and triggered a pandemic that has killed more than 5 million people around the globe.