What is different about Omicron?
It was first detected in Botswana and South Africa in November, with Omicron variants spreading around the world a few weeks ago, faster than any previously known coronavirus. While there is still much that scientists do not understand about Omicron, the difference is already creating an increase in new cases that could push some hospital systems to a halt.
Scientists first discovered the Omicron because of its unique combination of over 50 variants. Some of them were loaded with earlier variants such as Alpha and Beta, and previous tests showed that they could cause coronavirus to spread rapidly. Other genetic mutations were known to help coronaviruses escape their immune system.
Based on that reversal, and the alarming increase in Omicron cases in South Africa, the World Health Organization designated Omicron a “separate concern” on November 26, warning that the global risk posed by this “is very high.” Since then, exceptions have been identified in more than 90 countries. In early December, a California citizen who returned home from South Africa was identified as the first American to be invaded by Omicron. In Dec. 18, the Centers for Disease Control estimates that they make up 73 percent of all new infections in the United States. Omicron is rapidly gaining ground in most parts of the world, living up to the powers that scientists recognized when it was first discovered.
Is Omicron spreading faster than other types?
Yes. It has the potential to spread as much as two or three times as much as Delta.
The first evidence of Omicron's rapid spread came from South Africa, when Omicron quickly grew to dominate one province after another. In some countries, researchers have been able to catch Omicron prematurely on its rise, and the picture is the same: Omicron cases double every two to four days - much shorter than Delta required to double.
To monitor the spread of the Omicron, British researchers also observed what was happening in the homes of 121 people infected with the virus. They found that Omicron was 3.2 times more likely to cause home infections as was the case with Delta.
Researchers do not yet know why Omicron spread so easily. Another possibility is that it can easily attack cells; other possibilities include the ability to replicate once within cells.
Does non-infection in the past stop Omicron?
While most likely it provides protection against serious infections, non-infection with previous infections does little to prevent infections with Omicron. The first clue that Omicron could protect the immune system came from South Africa, where scientists estimated that at least 70 percent of people had been exposed to Covid-19 at some point in the epidemic. An unexpectedly large part of Omicron cases involve people who were previously infected.
By the time Omicron passed through England, British researchers similarly found that most people infected with the new virus had survived Covid. Researchers estimate that the risk of re-infection with Omicron is five times higher than in other species.
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To gain a deeper understanding of this increasing risk of re-infection, a number of scientists have studied the antibodies produced by people recovering from Covid-19. When they combine those antibodies in a container with other types, the immune system does a good job of preventing germs from invading human cells.
But when they combine those antibodies with the Omicron, it can still penetrate the cells most of the time. That means that the Omicron mutation alters the structure of the extra protein, when the immune system is trapped in the coronavirus.
This ability to escape the immune system is probably part of the explanation of why Omicron cases are repeated so quickly. While some types are released by the immune system, Omicron is effective in infecting more cells - making it more effective in infecting more people.
How much vaccine protects against Omicron infection?
Several studies show that a full vaccine and a stimulant gun provide strong protection against infection with Omicron. Without a booster, however, two doses of vaccines such as Pfizer-BioNTech or Moderna provide very little protection. (However, two doses of vaccine appear to protect against severe infections from Omicron.)
Scientists drew blood from people who had been fully vaccinated and mixed their antibodies with Omicron in a petrol container filled with human cells. Every vaccine tested so far has done a very bad job of making Omicron less effective than other types. And antibodies from people who received two doses of AstraZeneca or one dose of Johnson & Johnson vaccines seemed to do nothing against Omicron.
But when researchers tested the antibodies in people who had received boosterers from the modern vaccine Moderna or Pfizer-BioNTech, they saw a different picture. Increased antibodies prevent many Omicron viruses from infecting cells.
The researchers found a similar response when they looked at people who were fully vaccinated in two doses after Covid-19 infection: Their immune system was extremely strong against Omicron.
Real-world studies support the results of these experiments. In South Africa, researchers found that two doses of Pfizer-BioNTech vaccine were effective in combating only 33 percent of Omicron infections. Contrary to many alternatives, they found that its effectiveness was 80 percent.
In Britain, researchers found that people who received two doses of AstraZeneca vaccine did not enjoy any protection against Omicron infection six months after vaccination. Two doses of Pfizer-BioNTech are only 34 percent effective. But the Pfizer-BioNTech booster was 75 percent effective against infection.
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