Covid’s Origins: A House subcommittee opened its first public hearing on the possible origins of the pandemic, including a lab leak theory that’s the subject of intense political and scientific debate.They found that the original version of Omicron was 3.2 times as likely to cause a household infection as Delta was.
In other countries, researchers were able to catch Omicron earlier in its upswing, and the picture was the same: Omicron cases doubled every two to four days - a much faster rate than Delta.įor a closer look at how well Omicron spreads, British researchers also observed what happened in the households of 121 people who had been infected with the variant. The earliest evidence for Omicron’s swift spread came from South Africa, where Omicron rapidly grew to dominance in one province after another. Health Security Agency said in a recent report.
In some countries, those subvariants are replacing BA.2 roughly as fast as BA.2 replaced the original Omicron, the U.K. The original version of Omicron, known as BA.1, was two to three times as likely to spread as Delta, and BA.2 spread even more quickly.īA.4 and BA.5 may be the most transmissible versions yet. (The spring spike was smaller than previous surges in South Africa, however, and did not cause as many deaths.)ĭoes Omicron spread faster than other variants? The subvariants were first identified in South Africa in early 2022 and sparked a new wave of cases in the country this spring. During the week ending June 11, the two subvariants accounted for 21.6 percent of cases in the country, up from just 1 percent in early May, according to C.D.C. Two new subvariants, BA.4 and BA.5, have been gaining ground in the United States. One of them, known as BA.2.12.1, quickly outcompeted BA.2., becoming the dominant virus version in the country. In April, New York officials announced that two new subvariants, which evolved from BA.2, were spreading rapidly in the state. In the late winter and early spring, a different subvariant, known as BA.2, gained steam, becoming increasingly prevalent worldwide and the dominant variant in the United States. In the United States this winter, BA.1 and the highly similar BA.1.1 drove an enormous surge in new cases, which peaked at an average of more than 800,000 a day in mid-January, more than three times as high as the nation’s previous peak. Initially, the subvariant known as BA.1 was the most common. There are several genetically distinct versions of Omicron that have drawn particular attention. Today, the variant accounts for virtually all infections globally. 25, it made up three-quarters of all new infections in the United States, according to the Centers for Disease Control and Prevention. 26, warning that the global risks posed by it were “very high.”Īt the beginning of December, a California resident who returned home from South Africa was identified as the first American infected with Omicron. Other mutations were known to help coronaviruses evade antibodies produced by vaccines.īased on those mutations, along with a worrying rise in Omicron cases in South Africa, the World Health Organization designated Omicron a “ variant of concern” on Nov. Some of them were carried by earlier variants such as Alpha and Beta, and previous experiments had demonstrated that they could enable a coronavirus to spread quickly. Scientists first recognized Omicron thanks to its distinctive combination of more than 50 mutations. Over the winter, the variant caused a rapid rise in new cases that pushed some hospital systems to the breaking point. First identified in Botswana and South Africa in November 2021, the Omicron variant quickly surged to global dominance, faster than any previously known form of the coronavirus.
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