July 23, 2024

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Omicron variants will greatly reduce the effectiveness of COVID-19 vaccines?


Nature Hot Discussion: Omicron variants will greatly reduce the effectiveness of COVID-19 vaccines?



Brief Introduction:

Researchers are working hard to track the rapidly spreading new variant of the SARS-CoV-2 coronavirus.

In this variant, a large number of mutations found in other variants, including the Delta variant, were found.

The WHO named this variant Omicron, and the Omicron variant seems to be spreading rapidly in South Africa.

Will the Omicron variants pose a threat to the effectiveness of the vaccine?


The Omicron variant was first discovered in Botswana in early November, and since then it was discovered on a traveler who arrived in Hong Kong from South Africa.

Scientists are still trying to understand the characteristics of this variant. Is Omicron more contagious? Is it more deadly?

Is it easier to reinfect the recovered? Can it escape the immune response triggered by the vaccine? Will it cause more severe symptoms or conditions than other variants?


On November 25, the article was published in “Nature”, titled “Heavily mutated Omicron variant puts scientists on alert”.


Omicron variants will greatly reduce the effectiveness of COVID-19 vaccines?https://www.nature.com/articles/d41586-021-03552-w#correction-0


Penny Moore, a virologist at the University of the Witwatersrand in Johannesburg, South Africa, said, “We are groping to investigate,” and her laboratory is testing the potential of new variants to evade vaccines and immunity from previous infections.

There are rumors of re-infection and cases in people who have been vaccinated, but “it is too early to draw conclusions,” Moore added.


Richard Lessells, an infectious disease doctor at the University of KwaZulu Natal in Durban, South Africa, said at a press conference of the South African Ministry of Health on November 25, “We still have a lot of things we don’t know about this variant. The emergence of new variants makes We are a little worried.”


On November 26, the World Health Organization (WHO) designated the B.1.1.529 strain as the variant of interest based on the recommendations of scientists from the WHO SARS-CoV-2 Virus Evolution Technical Advisory Group and named it Omicron.

Omicron, along with Delta, Alpha, Beta and Gamma, is included in the WHO’s current list of variants.


The researchers also hope to measure the potential of this variant to spread globally – it may trigger new outbreaks or exacerbate the continued increase in infections caused by Delta.




Severe mutations


Researchers found B.1.1.529 in Botswana’s genome sequencing data. This variant is notable because it contains more than 30 changes in spike proteins .

Spike protein is the SARS-CoV-2 protein that recognizes host cells and is the main target of human immune response.

Many changes have already appeared in variants such as Delta and Alpha. These changes increase the infectivity of the virus and evade infection blocking antibodies .


In Gauteng Province, South Africa (the seat of Johannesburg), the number of cases of the Omicron variant has clearly risen sharply, which has also sounded a wake-up call for us.

According to Lessells, cases in the province increased rapidly in November, especially among schools and young people.

Genome sequencing and other genetic analysis conducted by a team led by Tulio de Oliveira, a bioinformatics scientist at the University of KwaZulu Natal, found that all 77 virus samples they analyzed came from the Omicron variant .

These samples were on November 12th. Collected from Gauteng on the 20th. Currently, researchers are analyzing hundreds of samples.


Lessells said that the Omicron variant has spike mutations that can be detected by genotyping tests, which provide results much faster than genome sequencing.

Preliminary evidence from these tests shows that the spread of the Omicron variant goes far beyond Gauteng. “We are worried that this variant may have spread across the country, ” Lessells said.

Omicron variants will greatly reduce the effectiveness of COVID-19 vaccines?






Vaccine effectiveness


In order to understand how threatening the Omicron variant is, researchers will closely follow its spread in South Africa and other regions.

Researchers in South Africa began to study the Omicron variant just like the Beta variant discovered at the end of 2020.


Moore’s team has already begun to study the Omicron variant, and they plan to test the Omicron variant’s ability to evade infection blocking antibodies and other immune responses.

This variant hides a large number of mutations in the spike protein region recognized by the antibody, which may reduce the effectiveness of the antibody .

Moore said that computer modeling even suggests that the Omicron variant can evade the immune system’s T cells . Her team hopes to get preliminary results within two weeks.


Aris Katzourakis, who studies virus evolution at the University of Oxford in the UK, said, “A more pressing question is-it has so many mutations, will it reduce the effectiveness of the vaccine?”.

Moore said that in South Africa, there have been cases of breakthrough infections among people vaccinated with Johnson & Johnson, Pfizer-BioNTech, and Oxford-AstraZeneca vaccines .

According to news reports, the two passengers quarantined in Hong Kong who tested positive for the Omicron variant were both vaccinated with the Pfizer-BioNTech vaccine.

One case was travel into Hong Kong from South Africa, and the other case was cross-infection during hotel quarantine.


Lessells said South African researchers will also study whether the Omicron variant causes more severe or milder disease than other variants. “The real key issue is the severity of the illness.”


The researchers said that so far, the threat posed by the Omicron variant outside of South Africa is far from clear.

Moore said that it is unclear whether the variant is more contagious than Delta because there are currently not many COVID-19 cases in South Africa. “We are now in a calm period.” She said. Countries where Delta is widely circulated should pay close attention to the Omicron variant. “We need to see how powerful this variant is and whether it will exacerbate the popularity of COVID-19,” Katzourakis said.










Omicron variants will greatly reduce the effectiveness of COVID-19 vaccines?

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