A series of latest studies have given people a glimmer of light from the dark cloud brought by the omicron variant: Although the number of confirmed cases has soared to a record high, the number of severe and hospitalized cases has not been the same.Some scientists said that the data indicates that the epidemic is entering a new chapter that is not so worrying.
“We are at a completely different stage now,” said Monica Gandhi, an immunologist at the University of California, San Francisco. “The new crown virus has always been with us, but I think the super immunity produced by omicron can help quell this pandemic.”
The Omicron mutant was discovered in South Africa a month ago, and experts warned that the situation may change. However, the data in the past week showed that under the influence of the two factors of the population’s general immunity and the large number of mutations, the severity of symptoms of omicron-infected patients has been much lower than that of previously infected patients.
A study from South Africa found that in the fourth wave of epidemics mainly caused by omicron, the probability of hospitalized patients developing severe illness was 73% lower than that of the third wave caused by Delta. “The data is quite reliable, and there is no strong correlation between the number of hospitalized cases and the number of confirmed cases,” said Wendy Burgers, an immunologist at the University of Cape Town.
Earlier, a large number of warnings regarding omicron were mainly due to the large number of mutations in the mutant strain, many of which appeared in the spike protein. Early data shows that these mutations allow the virus not only to easily infect people who have not been vaccinated, but also to break through people who have been infected with the new crown or have been vaccinated before. But the question remains, once it breaks through the first line of defense, how will omicron perform.
There are several factors that make this variant seem not as virulent as the previous virus. One of the factors is its ability to infect the lungs. Coronavirus infection usually starts in the nose and then spreads to the throat. A mild infection stops it in the upper respiratory tract, but if the virus enters the lungs, it usually causes more severe symptoms.
But five independent studies in the past week have shown that omicron is relatively less likely to infect the lungs. A joint study conducted by Japanese and American scientists showed that the lung damage of hamsters and mice infected with omicron was much lower than that of subjects infected with several previous variants, and the mortality rate was also lower. Another Belgian study came to a similar conclusion on Syrian hamsters.
Scientists studied a small number of lung tissue samples from patients collected during the operation and found that the growth rate of omicron in these samples was significantly slower than other mutant strains.
Burgers said that this change in toxicity may be related to changes in the structure of the virus.
“In the past, it used two different paths to invade cells, but now due to changes in the spike protein, it prefers one of them,” she said. “It seems to be more likely to infect the upper respiratory tract than the lungs.”
Burgers said this may mean that the symptoms caused by omicron are less severe, but it also means that the virus is more transmissible, because the virus multiplies faster in the upper respiratory tract and is therefore easier to spread.
“When you start to see all kinds of different data pointing in the same direction, you will be more convinced that we can fight omicron,” said Jessica Justman, an epidemiologist at Columbia University Medical Center.
Gandhi of the University of California, San Francisco said that although the new cases may reach a record level, she hopes that the high infectivity and low pathogenicity of omicron will herald the end of the epidemic. She pointed out that the results of another study published in Hong Kong last week showed that vaccinated omicron-infected individuals also had a strong immune response to other mutant strains. She said this may explain why the number of new cases in South Africa peaked rapidly.
“I hope this mutant strain can give people super immunity,” she said. “It is expected to end the epidemic.”
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