Scientists in South Africa said on Friday that the newest version of the coronaviruses appeared to spread more quickly than the previous version.
The researchers said that Omicron has a combination of contagiousness and ability to dodge the body's immune defenses. The contribution of each factor is not certain.
Carl Pearson, a mathematical modeler at the London School of Hygiene and Tropical Medicine who led the analysis, said they were not sure what the mixture was. It is possible that it is less transmissible than Delta.
Dr. Pearson posted the results. The research has not yet been published.
Researchers reported on Thursday that the new variant may not have immunity from a previous infection. It is not clear whether or not Omicron will evade protection by the vaccines.
Some experts think the outcome will be the same.
Akiko Iwasaki, an immunologist at Yale, said that it was scary that there were so many re infections.
The Omicron variant has appeared in over two dozen countries. There are at least 10 cases in the United States. President Biden said on Friday morning that the new measures announced this week should be enough to stop the spread of Omicron.
A Covid testing station is located at the O.R. Tambo International Airport.
The variant was first identified in South Africa and has quickly become the most common variant in that country. The number of new coronavirus cases in South Africa increased by 35 percent on Thursday and the proportion of positive test results increased.
Juliet Pulliam, the director of an epidemiological modeling center at Stellenbosch University in South Africa, who led the earlier research on immunity, said it was striking how quickly it took over.
According to the new estimates by the researchers, ovarian cases are doubling every three days in the province.
They compared the metric for Delta with the metric for the variant's Rt, which is a measure of how quickly a virus spreads. They found that Omicron's Rt is 2.5 times higher than Delta's.
The figure is dependent on both how contagious the variant is and its ability to sidestep the body's immune defenses once it reaches a new host.
The current vaccines may not be as effective against it as against previous versions, because of the Omicron variant, according to some researchers.
The new variant's ability to evade immunity was estimated by Dr. Pulliam and her colleagues in the research published on Thursday.
They reported an increase in re infections among people who had tested positive for the virus at least 90 days earlier, suggesting that the immunity gained from a previous bout with the virus was no longer as protective as it had appeared. The Omicron's spread in the country caused the increase in reinfections.
Dr. Pulliam said that a quirk of Omicron's genetic code made it easy to distinguish the variant from Delta in diagnostic tests.
If we hadn't had that, we would be several weeks behind where we are now in terms of recognizing that there was a new variant.
The team said it was a reasonable assumption that the reinfections they observed were caused by the new variant. The scientists noted that a spike did not occur when the Delta andBeta variant were dominant.
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Biden has a winter plan. As Omicron reaches the U.S., President Biden announced a new strategy that includes hundreds of family-centered vaccination sites, booster shots for all adults, new testing requirements for international travelers and insurance reimbursement for at- home tests.
Experts have differing views on boosters. Many public health experts have opposed plans to give Covid booster shots to all adults. As Omicron gains ground, researchers are changing their minds and now believe that the shots may be the best defense against the new variant.
Economic recovery is at risk. The global economy is in a state of uncertainty as new restrictions on travel and trade are making consumers less confident.
The risk of reinfection with the Omicron variant is roughly as high as the original version of the coronaviruses.
The people in Orange Farm received their Covid shot on Friday. Scientists say that the country is in the fourth wave of infections.
Vaccines are thought to produce higher levels of antibodies in the body than the coronaviruses. The immune system is capable of fighting off variant with a wider range of mutations, according to an immunologist at the Icahn School of Medicine at Mount Sinai in New York.
If the new variant is reinfecting people who have recovered from Covid, I don't think that there will be much of a difference in how Omicron responds to vaccines, said Dr. Krammer. It is not a good sign.
The severity of the first illness was not known by South African researchers. The immune system should be able to prevent the most severe symptoms in people who have had a previous infection or have been immunized.
She said that she was hopeful that these weren't going to result in severe disease. There may be a lot of infections, but they may be milder.
Scientists say that the fourth wave of infections in South Africa is centered in the province of the same name. According to the National Institute for Communicable Diseases of South Africa, the week-on-week increase in hospital admissions is higher than in previous waves.
The Delta wave clobbered Gauteng five months ago, so there's no doubt that this variant is causing significant numbers of re infections.
The percentage of children younger than 5 with total cases has risen sharply, and that may be because more adults are immunized now than in previous waves.
Dr. Jassat said that more children are being admitted to hospitals as a precautionary measure.
They wouldn't meet the criteria for admission later in the wave. She said that most hospitalized children are unvaccinated and live with their parents who have not been immunized.
Reporting from South Africa was contributed by Lynsey Chutel.
