One wave has not settled, another wave has arisen. The new crown virus will be forgiven again
Photo source: Weibo@China News
Although the virus changes abroad, it will not immediately affect China. But seeing these news, there is always a feeling of chest tightness and powerlessness. Humans have used all their strength, how come the enemy is getting more and more powerful? The virus is so smart, can we withstand it?
It’s not a mutation to be super strong
Instead only super strong variants are identified
In the more than two years of the new crown epidemic, we have also memorized many Greek letters and English abbreviations. From the early Alpha, Delta, to the current BA.2.12.1, it seems that every time I notice these virus changes, there are words “stronger” and “super strong”.
This is not the case that the new coronavirus is actively seeking new changes. Viruses mutate randomly and disorderly. Only the strong can stand out in the cruel competition and grab more chances to infect the human body. More virus mutations can’t infect people, and they can only be poisoned. Even if it is accidentally discovered by human detection, it will soon disappear in the long river.
The lucky few who change by chance can become the mainstream of the new coronavirus in the world and become the protagonists of media reports.
The new coronavirus has experienced the mainstream period of Alpha, Delta, Omicron BA.1, and Omicron BA.2. Today, BA.2 is still dominant in most countries, but judging from the trend, there are indeed 3 new “stronger mutants” that are slowly appearing.
Image source: covariants
21K in the picture is the original Omicron strain BA.1 and 21 L is BA.2. 22A is BA.4, 22B is BA.5, and 22C is BA.2.12.1, the protagonist of today’s news. They are all new variants of the Omicron base.
BA.2.12.1 is mainly concentrated in the United States, while BA.4 and BA.5 are mainly distributed in South Africa. Although a growth trend can be seen, it is still uncertain whether the three of them will replace BA.2 as the world’s leading mutant in the future.
Online ‘30% more infectious’ is inaccurate
BA.4, BA.5, BA.2.12.1, the prevalence of these three new variants in local areas shows that they are indeed powerful, otherwise they will not replace the original ones mutant strain.
Take BA.2.12.1 (red bar) as an example, it has been eating away at the sphere of influence that used to be BA.2 in the US for the past few weeks, and it will soon reach half of its infections accounted for.
Image source: CDC
We can express the growth of BA.2.12.1 using the concept Relative Growth Rate (RDR). During this time period, various statistics suggest that the RDR of BA.2.12.1 compared to BA.2 is between 25% and 38%. This is probably where 30% of top searches come from.
Strictly speaking, it’s not that BA.2.12.1 is 30% more contagious. It’s just that in the current US environment, the final propagation result of BA.2.12.1 is about 30% faster than the original BA.2. Because BA.2.12.1 spreads faster, it slowly became the mainstream of the virus.
Actually faster transmission does not mean stronger infectivity, because in addition to infectivity itself, differences in human immunization and control policies will also affect the actual transmission ability.
The infectivity of a virus is usually expressed by the R0 value (basic infection number). Refers to how many people a person infected with the virus can infect with no protection at all. It’s naked contagion, playing in a completely consistent environment.
In the early stage of the new crown epidemic, human beings did not have any immune protection ability, and only had a small impact on the physical isolation policy, so the mutations that can become mainstream are basically highly contagious. The R0 values are 1.4-3.8 for the original strain, 4-5 for alpha, 5.1 for delta, 7 for Omicron…
After Omicron, infectivity cannot be directly equal to transmissibility. Because the world has changed.
Strong immune escape is the key to fast spread
From around the time of Omicron, major countries in the world have achieved high levels of vaccination against COVID-19, which is equivalent to establishing a layer of active immunity.
The more important change is that Omicron has basically penetrated the protection of various countries, from the original part of people infected with the new crown to a round of almost universal infection. Although the statistics show hundreds of millions of new infections worldwide, more untested and unreported antigen tests have resulted in a large number of statistical gaps. It is estimated that two-thirds of people in the United States have experienced an infection.
Estimated true COVID-19 infection rate by age group in the United States
Image source: Nature
In the United States and many other countries in the world, there is already passive universal immunity against the new coronavirus, or the new coronavirus Omicron strain.
On this basis, if you want to defeat the same kind to win the competition, the strongest ability of mutants is no longer endogenous infectivity, but immune escape ability. Only if it can better defeat the human immunity that has been actively protected by vaccines and has experienced virus infection, can the new variant “win”.
BA.2.12.1, BA.4, BA.5 began to replace BA.2 and the original Omicron because of their stronger immune escape ability, and are expected to become world mainstream. Their true infectivity, or R0, is unclear.
Chinese scholars have played an important role in explaining the immune evasion capabilities of the three.
The team of Academician Xie Xiaoliang of Peking University has uploaded a detailed study on the immune evasion of the new variant strain on the preprint platform, which is expected to be published in Cell. This study confirms that Omicron virus can mutate specifically to evade the immunity brought by the original strain, and can also evade the immune protection from three-shot vaccination. The key to evading immunity is the L452 mutation. BA.2.12.1 is L452Q, BA.4/BA.5 is L452R.
For a long time in the future, the mutations that drain the mainstream of the new crown will still be immune evasion powerhouses.
Are the new mutations good for the world? is it bad?
Just experienced a round of Omicron’s baptism, and there are new mutations to escape immunity, it seems that the world will not be better.
Not quite.
The current mutation, which seems to appear frequently, is actually held by humans to a certain extent, and belongs to the “predicted mutation”.
Dr. Trevor Bedford, who is dedicated to the evolution of virus transmission, has roughly given this change pattern in a series of predictions about the new coronavirus, which has been gradually verified in the real world.
Image credit: Trevor Bedford speculation published April 7
Although the new coronavirus has many variations, it has a limited structure. Under the constant random attempts, the appearance of Omicron has brought the mutation to a new height, and it is difficult to play big tricks again.
In other words, the new coronavirus has found the most suitable survival mode for human society. In the short term (Trevor Bedford predicts that the epidemic period of Omicron will be 1.5 to 10.5 years) there will not be those uncontrollable mutations that we worry about, there will not be obvious fluctuations in pathogenicity, but only some evasion of immunity. Fine tune. That is, after Omicron, the next big mutation that will be named by Greek letters will not come easily.
Although these fine-tuning also make humans somewhat passive, they will not seriously affect the society and become a stable attack and defense of various humans and BA.xxxxxx.
You can also see the clues from the figures in the United States and South Africa in the last month. Under the influence of the new variant, the number of new infections has increased again, and many are repeated infections. But the number of hospitalizations and deaths did not rise significantly.
U.S. COVID-19 hospitalization curve, March 2020 to present
Image credit: Twitter @Eric Topol
Of course, even with fine-tuning, these immune escapes pose a major conundrum for our vaccine development.
Judging from the current rapid mutation, the special Omicron vaccine, which was specially launched for Omicron a few months ago, may not be able to work. Rapid changes make any special vaccine difficult. have become the yellow flowers of tomorrow.
In order to better increase active immunization of vaccines, the current implementation of multiple vaccine booster vaccinations may achieve better results (the vaccines developed for the original strains are more resistant to various mysteries Chron mutation). There should also be more optimized multi-stage vaccines in the future, or completely new vaccines that can span all variants.
What about China?
Many countries around the world have experienced the Omikron transit and have built passive immunity following tragic losses. However, only some people in a small number of areas in China have this passive immunity, and they can rely on vaccine protection in the future.
Now Shanghai and other places are fighting against BA.2, and there may be BA.2.12.1 coming in in the future, as well as other possible new variants. If our strict prevention cannot stop the virus, with the current limited vaccine protection, it is likely to usher in a tsunami of cases.
Fudan University School of Public Health published in Nature Medicine a modeling article by Omicron in China, which calculated that the number of hospitalizations, ICU admissions and The death toll has risen sharply. Among them, the peak ICU demand will be 15.6 times the current number of ICUs, and the total number of deaths will be about 1.55 million, of which 77% are people who have not been vaccinated.
Increasing vaccine coverage in the elderly population (vaccination of currently eligible individuals with available vaccines, including full course and booster shots) could reduce hospital admissions by 33.8%, ICU admissions A 54.1% decrease, and a 60.8% decrease in the number of deaths.
It is difficult for us to rapidly improve the treatment capacity of the ICU in the short term. In order to protect 1.55 million lives, the most important thing is to continue to promote vaccination.
More vaccine supplies, more advanced vaccination methods, and more types of vaccines can effectively increase the vaccination rate of the whole population, so as to have more confidence to meet possible changes in the future, Another victory against the epidemic.
This article reviewer
References
[1] Xie X, Cao Y, Yisimayi A, et al. BA. 2.12. 1, BA. 4 and BA. 5 escape antibodies elicited by Omicron BA. 1 infection[J] . 2022.
[2] Telenti A, Hodcroft E B, Robertson D L. The Evolution and Biology of SARS-CoV-2 Variants[J]. Cold Spring Harbor perspectives in medicine, 2022: a041390.< /p>
[3] https:https://bedford.io/talks/sars-cov-2-continuing-evolution-vrbpac/#/
[4] https:https://www.nature.com/articles/s41591-022-01855-7_reference.pdf
Planning
Planning: Eric | Producer: Feidi
Cover image source: Figure Worm Creative
Thanks to Dr. Yuge Wang for his content support