The first case of infection with the Omicron variant of the coronavirus has been reported in the United States, the Centers for Disease Control and Prevention announced on Wednesday.
The patient, a traveler who returned to California from South Africa on Nov. 22, is in isolation and aggressive contact tracing is underway. The individual was fully vaccinated and had mild symptoms that are improving.
The World Health Organization has warned that the risk posed by the variant, a new iteration of the coronavirus that was first identified in southern Africa, is “very high.” More than a dozen countries across four continents have detected the variant since it was first identified in southern Africa. Experts have said it was only a matter of time before the variant showed up in the United States.
Omicron carries more than 50 genetic mutations that in theory may make it both more contagious and less vulnerable to the body’s immune defenses than previous variants. More than 30 of the mutations are in the virus’ spike, a protein on its surface. Vaccines train the body’s immune defenses to target and attack these spikes.
Available vaccines may still offer substantial protection against severe illness and death following infection with the variant, and federal officials are calling on vaccinated people to get booster shots. The makers of the two most effective vaccines, Pfizer-BioNTech and Moderna, are preparing to reformulate their shots if necessary, but that will take time.
Following news of the variant’s spread in South Africa, countries around the world curtailed air travel to and from southern Africa, measures that officials there described as unduly punitive, especially in light of the fact that Western countries have failed to deliver sufficient vaccines and logistical support to the continent.
Dutch officials said on Tuesday that they identified cases of the variant a week before Friday, when 13 passengers who arrived on flights from South Africa tested positive for it, signaling that the variant was already present.
In South Africa, the variant accounts for most of the new daily cases reported in the nation’s most populous province, Gauteng, which is home to some 15 million people and the cities of Johannesburg and Pretoria.
The W.H.O. says the emergence of Omicron resulted from vaccine inequity in poor countries. Even so, some nations, including Britain and the United States, have renewed efforts to persuade citizens to get vaccine booster shots as quickly as possible.
In New York, Gov. Kathy Hochul has declared a state of emergency, slated to go into effect on Friday, that will allow the state to acquire supplies, take steps to reduce staffing shortages at hospitals, and limit elective procedures.
New York City on Monday imposed an updated mask advisory urging people to wear them inside public spaces, regardless of vaccination status. The measure stops short of being a requirement.
This developing story will be updated shortly.