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What are the difference between the mutated strains of COVID-19? α, β, γ, δ…
What are the difference between the mutated strains of COVID-19? The global COVID-19 epidemic is continuing, and the current COVID-19 vaccine has a declining effect on the COVID-19 variant strain. It seems that the Delta variant may form a new outbreak in some countries.
This strain has a strong spreading ability and a fast spreading speed, so how to deal with it has become a problem. Not only in some countries, but as the global COVID-19 situation is still severe, more and more COVID-19 mutant strains have become the focus of attention.
Since the COVID-19 epidemic swept the world in early 2020, the COVID-19 virus has spread wildly among the population. Because the virus will replicate the genetic genome during the transmission process, due to its inevitable replication errors, the virus genome has changed, resulting in mutant strains. Epidemic prevention has brought new challenges.
But not all mutations will bring huge risks, only some mutations will change the characteristics of the virus, making the virus more infectious and toxic. Which of these mutant strains are worthy of attention? What is their infectious ability? What is the scope of the spread? Does the existing vaccine have a protective effect on it? The Paper has comprehensively reviewed the latest information and authoritative websites.
According to the degree of risk, the WHO divides the COVID-19 variant strains into two categories:
- worrying variant strains (VOC, variant of concern)
- noteworthy variant strains (VOI, variant of interest)
The former has caused a large number of cases worldwide and has a wide range, and data confirms its transmission capacity, strong toxicity, or reduced effectiveness of vaccines and clinical treatments; the latter has confirmed cases of community transmission worldwide, or in multiple cases. The country has been discovered, but a large-scale infection has not yet formed.
At present, VOC is the mutant strain that has the greatest impact on the epidemic and the greatest threat to the world, including: Alpha, Beta, Gamma and Delta. Previously, in order to avoid stigmatization of relevant countries, the World Health Organization announced on May 31 that the names of the new coronavirus mutants that were first discovered in the United Kingdom, India and other countries were changed to Greek letters. Alpha, Beta, Gamma and Delta also Hence the name.
Alpha-spread rapidly at the end of 2020 and become the mainstream mutant strain in the first half of 2021
In November 2020, the Alpha mutant strain was detected for the first time in a September sample in Kent, UK. It swept the United Kingdom in December 2020, and became the dominant mutant strain in the United States in April 2021. It quickly squeezed the living space of other new coronavirus mutant viruses worldwide and became the main mutant strain. According to the “Global Shared Influenza Data Initiative” (GISAID) data, on May 17, Alpha accounted for 69% of the global infections of variant strains.
- Infectiousness Alpha is extremely infectious. According to a report from The New York Times on June 7, Gregory Towers, a virologist at the University of London, compared cells infected with Alpha with cells infected with early new coronavirus variants and found that cells infected with Alpha are better at hiding and more difficult to disturb the human immune system. At the same time, the patients infected with Alpha reacted more strongly, the patient coughed more, and the mucus with the virus would flow out of the mouth and nose-which also made the virus more contagious.
The latest research shows that Alpha’s “super-speeding” (super-speeding) has an important impact on the production of other new coronavirus variants. According to the latest report from the University of Oxford on July 22 this year, Alpha’s biological mutations have enabled it to “spread rapidly” across the UK at the end of 2020, and have an important impact on the spread of other variants.
- Vaccine efficacy AstraZeneca and Kexing vaccines are both effective against Alpha. According to a report on the website of Pharmacy Times on July 7, the Canadian Institute for Immunology Research found that the AstraZeneca vaccine is 90% effective against Alpha; according to the Thaiger news website on June 29, the Thai Public Health Department found that two doses of Kexing were administered. The effectiveness of the vaccine against Alpha ranges from 71% to 91%.
Beta-strong contagion, very strong immune escape ability
After Alpha, there was another Beta who was very immune to escape. Beta was first discovered in a sample from South Africa in May 2020, and soon became the most widely spread virus variant strain in South Africa. At present, Beta-related cases have been detected in 130 countries around the world. According to the latest data from GISAID, Japan was on the eve of the Tokyo Olympics. , A number of Beta cases were discovered on July 21.
- Infectivity Beta is highly infectious and is good at avoiding tracking by the human immune system. According to the advisory board news network, Beta is more transmissible and more resistant to antibodies than the early COVID-19 mutant strains. Beta is about 50% more infectious than the original new coronavirus, and the hospitalization rate, ICU occupancy rate and death risk are higher. According to a report by the British Broadcasting Corporation (BBC) on July 21, Beta carries the N501Y mutation, which enhances its infectivity; in addition, the E484K mutation it carries can help it avoid tracking by the immune system.
But Beta’s infectious ability is actually not as good as Delta. According to the aforementioned report on the Advisory Board News Network, Lawrence Young, a virologist and professor of oncology at the Warwick School of Medicine at the University of Warwick in the United Kingdom, said, “Delta outperforms Beta in terms of spread, but Beta will continue to exist.” According to the latest data from GISAID, On July 27, Beta accounted for only 0.286% of global infections.
- Vaccine efficacy Pfizer vaccine has better resistance to Beta. According to the BBC report, the research data of Pfizer vaccine in Qatar shows that its effective rate against Beta is 97%. And according to Zhou Yebinwen, a columnist of “Intellectuals” and a doctor of immunology, the immune escape of Beta mutant strains is obvious, but it is not a complete immune escape. Many vaccines can still play a very good protective effect, especially for severe cases. Protection.
Gamma-the biggest threat to the outbreak in South America
The Gamma mutant strain was first found in samples from Brazil in November 2020. It accounted for 76% of South American COVID-19 cases in June 2021. It is the most important COVID-19 strain in South America and has spread to the United States and the United Kingdom. 75 countries including Russia.
- Infectious Gamma mutant strains are highly infectious and may cause re-infection. According to the US “Business Insider” website reported on June 9th, Gamma is twice as infectious as the original new coronavirus. On April 23, the British “Guardian” quoted Peruvian epidemiologist Antonio Quispe as saying: “Gamma is not only more contagious, but also has the possibility of secondary infection, thereby reducing the risk of vaccines. Effectiveness.”
- Vaccine effectiveness However, the effectiveness of the vaccine against Gamma is still high. “Business Insider” article stated that Pfizer and AstraZeneca vaccines may be effective against Gamma. In the Brazilian trial, the effectiveness of Johnson & Johnson’s vaccine against Gamma was 68%. More research on the effectiveness of Gamma vaccines is still in progress.
Delta-the most infectious mutant strain to date
Among all the new coronavirus mutants that have emerged today, the most dangerous non-Delta is none other than Delta. Delta was first discovered in India at the end of 2020 and was the main mutant strain that caused the second wave of outbreaks in India in April this year. It spreads all over the world, raging in India, Britain and other countries. According to GISAID data, as of July 26, Delta accounted for 84% of infections in Asia, 97% of infections in the UK, and 80% of global infections. The WHO and the European Centers for Disease Control and Prevention jointly released an epidemic report on the 23rd, stating that according to current trends, the delta strain will become the world’s most important variant of the new coronavirus in the next few months, unless there is more competition. The strong strain appears, otherwise the delta strain will continue to spread and replace other mutant strains.
- Infectivity It is obvious that Delta is more infectious than any previous COVID-19 mutant strain, but there is no detailed data to show whether it will cause more serious diseases. Delta is 50% more infectious than Alpha, and it is also twice as infectious as the original new coronavirus. According to the “Washington Post” report on July 23, the Public Health Agency of England (PHE) found that Delta-related cases have a higher hospitalization risk, which is twice that of the Alpha mutant strain. At the same time, experts believe that more evidence is needed to explore its toxicity.
- Vaccine efficacy The vaccine is still effective against Delta, but there are uncertainties. According to a report from the Wall Street Journal on July 27, a study published in the New England Journal of Medicine in July showed that Pfizer vaccine and AstraZeneca vaccine are very effective against Delta after two doses. . After two doses of vaccine, the effective rate of Pfizer vaccine to prevent Delta was 88%, and after one dose, the effective rate was 36%. The effectiveness of preventing delta after two doses of AstraZeneca was 67% and 30% after one dose. An article on July 27th in the top international medical journal “Nature” pointed out that in the above study, the effectiveness of Pfizer vaccine and AstraZeneca vaccine on Delta is not as effective as that on Alpha. The current vaccine is effective for Delta. There is still uncertainty about sex.
(source:internet, reference only)