Wave after wave, wave after wave. The new coronavirus has mutated again.
Image source: Weibo @ China News Network
Although the virus changes abroad, it will not immediately affect China. But seeing these news, there is always a feeling of chest tightness and weakness. Human beings have exhausted all their strength, why is the enemy fighting harder and harder? The virus is so clever, can we still withstand it?
It's not super strong in a single mutation
Rather, only super mutants can be recognized
In the more than two years since covid-19, we have also memorized a lot of Greek letters and English abbreviations. From the early alpha, delta, and now BA.2.12.1, it seems that every time these virus changes are noticed, there are words "stronger" and "super strong".
This is not the new crown virus actively seeking new changes. Viruses are randomly and disorderly mutated, and the strong can stand out in the cruel competition and seize more opportunities to infect the human body. More virus mutations cannot infect people, and can only be poisoned. Even if it is accidentally detected by humans, it quickly disappears into the long river.
A few lucky people who have changed by chance can become the mainstream of the world's new crown virus and become the protagonists of media reports.
The new crown virus has experienced the mainstream period of Alpha, Delta, Omikron BA.1, and Omiqueron BA.2. TODAY, BA.2 is still dominant in most countries, but from the trend point of view, there are indeed 3 new "stronger variants" slowly emerging.
Image source: covariants
The 21K in the picture is the original Strain OF Omikeron BA.1, and the 21 L is BA.2. 22A is BA.4, 22B is BA.5, and 22C is the protagonist of today's news, BA.2.12.1. They are all new variants based on Theomilon.
BA.2.12.1 is mainly concentrated in the United States, while BA.4 and BA.5 are mainly distributed in South Africa. Although we can see the growth trend, it is uncertain whether the three of them will replace BA.2 as the world's leading variant in the future.
The "30% higher contagiousness" transmitted online is not very accurate
BA.4, BA.5, BA.2.12.1, the prevalence of these 3 new variants in local areas, indicates that they do have strength, otherwise they will not replace the original mutants.
Take BA.2.12.1 (red bars), for example, which has been encroaching on the original BA.2 sphere of influence in the United States for the past few weeks, and is about to reach half of the infections.
Image source: CDC
We can use the concept of relative growth rate (RDR) to express the growth of BA.2.12.1. During this time, different statistics considered the RDR of BA.2.12.1 to be 25% to 38% compared to BA.2. This is probably the source of 30% of the hot search.
Strictly speaking, this is not 30% more contagious than BA.2.12.1. However, in the current US environment, the final spread of BA.2.12.1 is about 30% faster than the original BA.2. It is precisely because BA.2.12.1 spreads faster that it has slowly become the mainstream of the virus.
Faster actual transmission does not mean that it is more contagious, because in addition to the contagiousness itself, different policies on human immunization and control will also affect the actual transmission capacity.
The infectivity of the virus is usually expressed in terms of the value of R0 (the basic number of infections). Refers to how many people can infect a person with the virus infected with the virus infected with no protection. It's a nakedly contagious competition, played in perfectly consistent circumstances.
In the early days of the new crown epidemic, humans did not have any immune protection capabilities, only a small impact of physical isolation policies, so the mutations that could become mainstream were basically highly contagious. R0 values are 1.4~3.8 for the original strain, alpha 4~5, Delta 5.1, Omiqueron 7...
After Omikron, contagiousness cannot be directly equal to the ability to spread. Because the world has changed.
Strong immune escape is the key to fast transmission
Since the Omi kerong period, the new crown vaccination in major countries in the world has reached a high level, which is equivalent to establishing a layer of active immunity.
The more important change is that Omi kerong basically broke through the protection of various countries, from the original part of the population infected with the new crown, to an almost universal infection. While statistics show hundreds of millions of new infections worldwide, more are untested and uninported after antigen testing, resulting in a large number of statistical gaps, and it is estimated that 2/3 of people in the United States have experienced infections.
Estimate the true rate of COVID-19 infection at all ages in the United States
Image credit: Nature
In the United States and many other countries in the world, there is already passive universal immunity to the new crown virus, or the New Coronavirus Olmicoren strain.
On this basis, if you want to beat the same kind to win the competition, the strongest ability of the mutant strain is no longer endogenous contagious, but immune escape ability. Only by better defeating the human immunity that has been actively protected by vaccines and experienced in viral infections can the new mutant strain "win".
BA.2.12.1, BA.4, BA.5 is because of the more powerful immune escape ability, began to replace BA.2 and the original Omi kerong, is expected to become the mainstream of the world. Their true contagiousness, also known as R0, is unclear.
Chinese scholars have played an important role in illustrating the immune escape capabilities of the three.
A team of academicians Xie Xiaoliang at Peking University has uploaded an informative study of the new variant strain evading immunity on the preprint platform, which is expected to be published in Cell. The study confirmed that the Omiljung virus can mutate specifically evade immunity brought by the original strain, as well as immune protection from three doses of vaccination. The key to evading immunity is the L452 mutation. BA.2.12.1 is L452Q and BA.4/BA.5 is L452R.
For a long time to come, the mutation that drains the mainstream of the new crown will still be immune to escape the strong.
Is the new mutation good for the world? Is it bad?
Having just experienced a round of the baptism of the whole people of Aomi Kerong, and having a new mutation to evade immunity, it seems that the world will not be good.
Not entirely.
The current mutation, which seems to appear frequently, is actually pinched by humans to a certain extent, and belongs to the "predicted mutation".
Dr. Trevor Bedford, who has devoted himself to the evolution of virus transmission, has outlined this pattern of change in a series of predictions for the new crown virus, which is gradually being verified in the real world.
Image credit: Trevor Bedford's april 7 public speculation
Although the new crown virus has a variety of variants, it is limited in structure. Under the continuous random attempts, the emergence of Aomi Kerong has brought the mutation to a new height, and it is difficult to play a big trick.
Or that the new crown virus has found the most adaptable mode of survival for human society. In the short term (Trevor Bedford predicts that the epidemic period of Aumechjong will be 1 1/2 to 10 and a half years), there will be no uncontrollable mutations that we fear, no obvious fluctuations in pathogenicity, but just some fine-tuning to evade immunity. That is, after Omikeron, the next big mutation that will be named by the Greek alphabet will not come easily.
Although these fine-tuning also make humans a little passive, they do not seriously affect society, and become a stable attack and defense of various humans and BA.xxxxxx.
The last 1-month figures in the UNITED States and South Africa also show that the number of new infections has increased under the influence of new variants, and many are repeat infections. But hospitalizations and deaths have not increased significantly.
COVID-19 hospitalization curve in the U.S. from March 2020 to the present
Image credit: Twitter @Eric Topol
Of course, even with fine-tuning, these immune escapes have caused major problems in our vaccine development.
Judging from the current rapid mutation, the Special Vaccine of Omikejong, which was specially launched for Omikejong a few months ago, may not be able to play a role, and the rapid change makes any special vaccine a thing of the past.
To better increase active vaccine immunization, the current implementation of multiple vaccines may achieve better results (vaccines developed for the original strain are more resistant to various Omilon mutations). In the future, there should also be more optimized multi-stage vaccines, or new vaccines that can cross all variants.
What about China?
Many countries in the world, having experienced the crossing of the Omiljung, have established passive immunity after the tragic losses. Only a small number of people in China have this passive immunity, and the future can rely on vaccine protection.
Now that Shanghai and other places are fighting BA.2, there may be BA.2.12.1 in the future, as well as other possible new variants. If our strict protection against the virus cannot be stopped, with the current limited vaccine protection, it is likely to usher in a tsunami of cases.
An Opichron modeling article published in Nature Medicine by the School of Public Health of Fudan University calculated that COVID-19 would lead to a collapse of the healthcare system, with a significant increase in hospitalizations, ICU occupancy and deaths. Among them, the peak demand for ICUs 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 unvaccinated.
Increasing vaccine coverage among the elderly population (vaccinating currently eligible people with existing supplies of vaccines, including full and booster vaccinations) could reduce hospitalizations by 33.8 percent, ICU occupancy by 54.1 percent, and deaths by 60.8 percent.
It is difficult for us to quickly improve the ICU's ability to treat in the short term, and in order to protect 1.55 million lives, the most critical thing is to continue to promote vaccination.
More vaccine supply, more advanced vaccination methods, and richer vaccine types have effectively increased the vaccination rate of the whole people, so that we can have more confidence to meet possible changes in the future and achieve another victory in the fight against the epidemic.