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  • Omicron promises to end the epidemic?The World Health Organization warns of mutations

  •  Release time: 2022-01-06 Clicks: 865  
  • Hu Ruoyu, Xinhua News Agency

    The mutant Omicron strain of coronavirus, while spreading like wildfire around the world, appears to be far less severe than initially feared, according to a number of new studies。Some scientists have speculated that the outbreak is entering a new, less worrisome phase, and that Omicron's high infectivity and low pathogenicity could signal "the beginning of the end" of the outbreak.。

    However, the World Health Organization's European regional official warned on the 4th that the surge in global infection rates could increase the risk of the virus mutating and even emerging more dangerous mutated strains。

    People attend the New Year's Eve celebration at Times Square in New York, the United States, December 31, 2021。Attendance at New York's New Year's Eve celebrations has been limited and visitors are required to wear masks and be fully vaccinated, amid a surge in confirmed cases caused by the mutated Omicron strain of the virus。Photo by Wang Ying/Xinhua News Agency

    It won't easily infect the lungs

    The main concern in the scientific community was that Omicron carried a large number of mutations, many of which occurred in spike proteins, which could not only easily infect unvaccinated people, but also bypass the antibody response triggered by infection recovery and the COVID-19 vaccine, with potentially serious consequences。But for more than a month, despite record numbers of confirmed cases, there has been no significant increase in severe and hospitalized cases。

    Infection with the novel coronavirus usually starts in the nasal cavity and then spreads to the throat。Mild symptoms generally mean that the virus only infects the upper respiratory tract, and more severe symptoms can occur if it invades the lungs。Omicron does not infect the lungs as easily as previous strains。

    According to Bloomberg News reported on the 4th, this characteristic of the Omicron strain has been confirmed in the results of five different studies published in the past week。

    Among them, a South African study found that after the fourth wave of Omicron, compared with the third wave of Delta strain in South Africa, the likelihood of severe illness requiring hospital treatment was reduced by 73%。

    Wendy Bergs, an immunologist at the University of Cape Town, said: "The data are now very convincing that the number of hospital admissions and confirmed cases are 'decoupling'.。”

    A joint study by scientists in Japan and the United States has shown that hamsters and mice infected with Omicron suffer much less lung damage and are less likely to die than previous strains。A Belgian study had similar results: Syrian hamsters infected with other strains of the virus developed particularly severe symptoms than Omicron。

    Scientists in Hong Kong, China, studied lung tissue samples from COVID-19 patients and found that Omicron "grew" more slowly in these samples than other strains of the virus。

    People carry shopping bags as they walk down Oxford Street in London, Britain, December 26, 2021。Steven Powys, the NHS's national medical director, warned that the health service was on a "war footing" as the Omicron strain swept across the country.。Photo by Li Ying/Xinhua News Agency

    Dual factors reduce toxicity

    According to Bloomberg, the severity of Omicron is much lower than that of previous strains, and is the result of a combination of large mutations in the virus itself and widespread immunity。

    The changes in virulence are likely to be linked to changes in the structure of the virus, Dr. Burgess said。The mutation in the spike protein of the Omicron strain makes it more likely to invade cells through one route, rather than the two routes commonly used by previous strains。"It (Omicron) seems to infect the upper respiratory tract more than the lungs。However, the Omicron strain usually replicates more in the upper respiratory tract, making it more contagious。

    In terms of immune factors, although Omicron is better at bypassing the antibody response as the first line of defense, recent studies have shown that it has difficulty avoiding the second line of defense, T cells and B cells, produced after vaccination or recovery from an epidemic。If antibodies fail to stop the infection, T cells attack the virus once it has entered the cell。

    When Burgs and his colleagues studied blood cells from COVID-19 patients, they found that 70 to 80 percent of the T-cell responses in Omicron patients were preserved compared to previous strains。This means that in people who have been vaccinated against COVID-19 or who have been infected in the past six months, T cells are more likely to recognize Omicron and quickly fight it off。More follow-up studies, if supported, could explain why Omicron is less symptomatic than other strains, Dr. Burgess said。

    Monica Gandhi, an immunologist at the University of California, San Francisco, said the results of another study published in Hong Kong last week showed that people who were infected with omicrone after completing the vaccine developed a strong immune response that was strong enough to ward off other strains。Might this explain why the fourth wave of the outbreak in South Africa peaked so quickly。

    "My hope is that this mutant will stimulate enough human immunity to end the pandemic," she said。”

    The risk of dangerous mutation remains

    However, the researchers also noted that despite the milder symptoms of Omicron infections, if the number of cases continues to surge, the number of hospitalizations and deaths will continue to rise, even if the increase is slower。

    Since the outbreak began, the cumulative number of confirmed cases in Europe has passed 100 million, with more than 5 million new cases in the last week of December alone。Catherine Smallwood, WHO's European regional official, said on the 4th that this almost "dwarfs" previous waves of outbreaks.。

    "We are at a very dangerous stage," she told AFP. "Infection rates are now rising dramatically in Western Europe and the overall impact (of Omicron) is unclear.。”

    The number of new confirmed cases in a single day in Britain exceeded 200,000 for the first time on Thursday, pushing the health care system into crisis。Smallwood expects the same to happen in other European countries as Omicron pushes up the number of cases。

    Smallwood said the impact of Omicron compared to the Delta strain "is likely to decrease the risk of hospitalization on an individual level," but overall, the threat may be greater because of the large number of infections。

    "The more widespread Omicron is, the more people are infected, the more copies are made, and the more likely new variants are to arise," Smallwood said. "Right now, Omicron is still deadly and can cause death...Maybe a little less severe than Delta, but who knows what kind of mutant strain might emerge next。”