Omicron has sparked alarm both internationally and in the United States, where the variant and its mutations accounted for 100 percent of new infections during the week ending Feb. 19, according to the most recent data from the Centers for Disease Control and Prevention. It has an unusually high number of mutations that make it significantly more contagious and capable of eluding the body’s first line of immune defenses. Omicron’s sublineage BA. 1 currently accounts for more than 75 percent of cases in the United States while BA.2. accounts for more than 3 percent, the data shows.
Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security, previously had said omicron “is not something that can be avoided.”
“Most people are going to get infected with omicron — including those who are vaccinated, including those who are boosted,” he said during the surge. “We now have to think about covid-19 in two different ways — as a mild disease in the vaccinated and as something that is still a problem for the high-risk unvaccinated.”
World leaders responded to the recent surge by placing restrictions on travel, ramping up vaccination and booster drives, increasing testing and encouraging an already pandemic-fatigued public to double down on measures including wearing masks and social distancing. Although studies indicate that omicron has been producing milder infections than other variants, the sudden swell of cases and large number of people who remain unvaccinated has still overwhelmed some strapped health-care systems.
Where has omicron been confirmed?
Omicron was first reported in late November, but its exact origin is still unknown. South Africa confirmed on Nov. 25 that scientists there had detected a worrying variant. Days later, other nations including the Netherlands said they had reviewed genetic sequencing data and found that the variant was already circulating within their borders at the same time as when South Africa raised the alarm. The World Health Organization soon listed it as a “variant of concern.”
In South Africa, where official statistics show that more than 42 percent of the adult population is fully vaccinated, the variant spread rapidly. By Dec. 14, the positivity rate hit 34.9 percent. However, by late December, South Africa’s top infectious-disease scientist said that the country had passed the peak of new omicron cases.
The first confirmed case in the United States was reported in California on Dec. 1, and within weeks, it had been detected in all 50 states.
By late December, the seven-day daily average coronavirus case count in the United States had surpassed the delta-driven summer surge, Washington Post figures show. And, by the next month, the number of new daily cases had surpassed 700,000. But cases and hospitalizations have significantly declined. As of Feb. 23, cases had dropped to about 75,000 per day, the CDC said, though data shows the virus is still circulating throughout communities in the United States.