May 28, 2022

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The virulence of coronavirus mutant strain B.1.1.7 has not increased

The virulence of coronavirus mutant strain B.1.1.7 has not increased (Lancet new evidence)

The virulence of coronavirus mutant strain B.1.1.7 has not increased.  In the more than a year of the new coronavirus (SARS-CoV-2) pandemic, researchers around the world have sequenced tens of thousands of epidemic strains of the new coronavirus.

The virulence of coronavirus mutant strain B.1.1.7 has not increased (Lancet new evidence)

In recent months, some variants of SARS-CoV-2 have been detected. Because genome mutations may affect the transmission ability of the virus, the sensitivity to vaccines, and the pathogenicity to humans, these strains are called variants of concern (VOC).

In the context of the global pandemic of the new coronavirus, these variants have attracted great attention from countries around the world. Now the variant strain (VOC) that deserves attention has become one of the most popular phrases, and the English abbreviation VOC of this phrase has also become popular. This article will use the English abbreviation VOC (Variants Worthy of Concern).

When the SARS-CoV-2 VOC B.1.1.7 was first discovered in the United Kingdom in December 2020, unconfirmed propaganda about the spread and virulence of the variant was followed. According to a research paper published in The Lancet Infectious Diseases (The Lancet Infectious Diseases) recently (12th of this month), the results of a hospital-based study in London, UK show that VOC B.1.1.7 and Severe disease is not related, that is, the virulence of the mutant strain is not enhanced compared with the original strain.

The New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG) in the United Kingdom is an advisory organization that is responsible for providing consultation and advice to the British Ministry of Health and Social Care. In a report (Note) published by “NERVTAG” on January 21, 2021, the advisory group concluded that compared with the non-VOC infection of the new coronavirus, the infection of the new coronavirus variant (VOC) B.1.1.7 is The increased risk of death is related, which is a realistic possibility. The risk ratio of death between VOC-infected persons and non-VOC-infected persons was 1.65.


This conclusion is based on the analysis of deaths related to COVID-19 (new coronavirus pneumonia) in several hospitals in the UK. The study published in January this year has no direct evidence that viruses of the B.1.1.7 lineage are associated with an increased risk of hospitalization or death.

This conclusion is based on a statistical analysis of reported mortality of individuals infected with VOC B.1.1.7 or non-VOC viruses. For example, in one study, the relative risk of death was 1.35 (95% confidence interval 1.08-1.68).

In another study, the average rate of case-fatality caused by VOC viruses or non-VOC viruses was 1.36 (95% confidence interval 1.18-1.56). These differences are actually very small, but there is a large confidence interval: from no impact to impact. The author points out that the absolute risk of death is still very low.

Statistics are calculated by analyzing a limited data subset (8%) of all COVID-19-related deaths, so there may be errors. In addition, there does not seem to be an increased hospitalization risk associated with VOC virus infection.


The interpretation of this report should be that it is mainly used as an early warning to continue the genomic monitoring of the virus’s VOC related to the risk of death, rather than immediately drawing a causal conclusion.

In this new study, published recently in “The Lancet”, the PCR-positive samples of inpatient patients collected in London from November 9 to December 20 were analyzed. Among them, 341 cases (58%) were infected with VOC B.1.1.7, and 143 cases (42%) were infected with the original virus (non-VOC). The results of the statistical model showed that there was no correlation between severe disease and death and VOC B.1.1.7.

It is hoped that these new research results can begin to reverse the disturbing statement made in the previous report that the virulence of VOC B.1.1.7 is 50% higher than that of the original strain. There has never been conclusive evidence for this type of conclusion, but it has been widely publicized by the mainstream media as the final conclusion.

Unfortunately, the authors of the aforementioned report continue to promote the idea that the B.1.1.7 virus is more contagious. Their conclusion is based on the increase in viral RNA levels in patient samples detected by RT-PCR (the PCR cycle threshold for VOC-infected patients is 28.8, and the corresponding threshold for non-VOC-infected patients is 32.0) and genome sequencing reads (1280 vs 831). ).

The increase in viral load determined by these methods may be a sign of an increase in the fitness of the virus, but it cannot prove an increase in transmission capacity. It is not clear whether patients infected with VOC spread more infectious virus, which may be consistent with the increased transmission capacity. Before completing such an experiment, it can only be speculated that VOCs such as B.1.1.7 have increased transmission.



Darwin’s theory of evolution tells us that genes that do not have an evolutionary advantage in nature will be eliminated, and species that do not have an evolutionary advantage will be eliminated. Generally speaking, in the process of evolution and mutation, viruses will develop towards lower virulence and greater infectivity.

Low virulence and strong infectivity are beneficial to the virus itself: it is good for the virus to live in the host for a long time, multiply in large numbers, and “infect” more hosts, so that the virus has more chances of survival.

This is a long-term inevitable trend, a high probability event, but in a short period of time or some local scope, this trend may not be able to become a reality immediately. Therefore, the specific situation needs to be analyzed in detail.

However, if a certain conclusion confirms the facts that contradict the above-mentioned high probability development trend, we often need to be more cautious when drawing conclusions.


(source:internet, reference only)

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