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A number of new studies confirm the silver lining of Omicron variants: Even if the number of cases climbs to record levels, the number of severe cases and hospitalizations is not the case.
Some scientists say these data indicate a new and less worrying chapter in the pandemic. “Now we are at a completely different stage,” said Monica Gan, an immunologist at the University of California, San Francisco.
“The virus will always be with us, but I hope this variant can induce enough immunity that the Omicron variant was discovered in South Africa more than a month ago. Experts warned that it will take a long time to change the situation, but last week The data showed that the combination of extensive immunity and numerous mutations resulted in a virus that was much more severe than the disease caused by previous iterations.
A study conducted in South Africa found that patients admitted during the fourth wave dominated by the virus omichron were 73% less likely to have serious illness than those admitted during the third wave dominated by delta.
University of Cape Town immunologist Wendy Burgers (Wendy Burgers) said: “The data on hospitalization and’case decoupling’ is very strong now.”
Initially, most of people’s concerns about Omicron were due to the large number of mutations in this variant, many of which are Spike proteins. The part of the protein found is not only easy to infect unvaccinated people, but also bypasses previous infections and vaccines. reaction.
It broke through these first lines of defense. Compared to the previous wave of Covid19, several factors seem to make Omicron variants less toxic or less toxic. The ability of the virus to infect the lungs. Covid infection usually starts in the nose and spreads to the throat.
Mild infections do not extend far beyond the upper respiratory tract, but when the virus reaches the lungs, it is usually the most serious and symptoms appear.
But five independent studies last week showed that this variant is not as susceptible to lung infections as previous variants. In a study preprinted online by a large consortium of Japanese and American scientists, hamsters and mice infected with omicron developed serious illnesses due to the early iterations of the virus. A small amount of lung tissue samples were collected from patients during the operation and it was found that Omicron grew slower in these samples than other variants.
Bergs said that this change in virulence may be related to changes in the anatomical structure of the virus. The pathway into the cell, now it prefers one of these pathways because of all the changes in the spike protein,” she said.
It seems to prefer to infect the upper respiratory tract rather than the lungs. Burgers said this may mean a less serious infection, but it is also easier to spread because the virus replicates more frequently in the upper respiratory tract, from where it can more easily spread the second line of defense against previous vaccines and infections: cells and cells .
If antibodies cannot prevent infection in the first place, then once the virus enters the body’s cells, T cells are responsible for attacking the virus. In a recent study by Burgers and colleagues, scientists used white blood cells from Covid patients to show that approximately 70-80% of T cell responses were retained compared to previous strains. This means that for those who have been vaccinated or infected with Covid in the past 6 months, their T cells are likely to recognize omicron and repel it relatively quickly.
This latest research needs further research. If it can withstand additional scrutiny, it can explain why the current infection seems to be milder than the previous wave of viruses.
Jessica Jessman, an epidemiologist at Columbia University Medical Center, said: “When you start to see different types of data all pointing in the same direction, you start to feel more confident that it will hold up.”
However, with the surge in cases, the absolute number of hospitalizations and deaths will continue to rise, even if these numbers increase more slowly.
“If your denominator is large, because many people are infected, you will still end up with many people going to the hospital and needing care,” Jasman said.
Gandhi of the University of California, San Francisco said that although the number of cases may be record-breaking, another study held in Hong Kong last week showed that the combination of highly infectious omicron and mild infection may herald the onset of the disease. Patients vaccinated with the Omicron vaccine also caused a strong immune response to other versions of the virus.
This may explain why the number of cases in South Africa quickly peaked.
“I hope this mutation can produce deep immunity in the population.” I hope the epidemic will end soon. “
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