Variant virus “tortures” the new crown vaccine

After the northern hemisphere enters the cold winter, a new wave of epidemics has swept across the globe. A more serious practical question lay before all countries: are the first batch of “seed players” such as Pfizer vaccine and Modena vaccine, which took the lead in emergency clearance, to be effective against the greatly mutated new coronavirus?

As of November 2020, vaccine orders from various countries have reached 9.6 billion doses. The effectiveness of a vaccine depends not only on its effectiveness against the virus, but also on side effects, antibody maintenance time, and so on.

Can the vaccine target a variant virus?
Since the United Kingdom, South Africa, and Nigeria independently discovered in mid-to-late December the new coronavirus that has spread significantly in their countries, despite the continuous suspension of navigation and national lockdown measures, more and more other countries have reported that their countries have been invaded by the above-mentioned mutant viruses.

British officials confirmed that this variant virus, which has dominated in London and other places, has a spreading rate of about 70% higher than that of ordinary viruses.

The World Health Organization reassuringly stated that this is a part of the development and evolution of the new crown epidemic. There is no need to worry too much: the virus does seem to be more easily transmitted after it is mutated, but there is no evidence that the mutated virus can make the host’s symptoms worse.

Anthony Fauci, the top anti-epidemic expert in the United States, expressed confidence in the current vaccines. He said that the mutation of most viruses such as influenza virus will not interfere with the function of the vaccine, and the new crown vaccine is not like the flu vaccine, which is easily affected by the change of the virus. “The rate of mutation of the new coronavirus is not as fast as that of the influenza virus. Pfizer and Modena’s vaccines are different from past injections and are very likely to resist mutation.”

Moncef Sloy, the chief scientific adviser of the U.S. government’s vaccine development “Action Curvature Action” program, also said that destroying the vaccine requires multiple changes in the genetic code of the virus, and one or two mutations are not enough to cause damage.

“Although it has been confirmed that the infectivity of the new coronavirus has increased after mutation, it does not mean that its pathogenicity has also increased. There is no direct evidence that the new coronavirus can make the vaccine invalid after the mutation.” A researcher engaged in antiviral immunity research. Of medical workers summed it up like this.

He said that after the mutation of the new coronavirus, it has not had a serious impact on the current detection methods and treatment methods. The inactivated vaccine against the new crown can still cover the mutated virus and has a certain immune protection effect.

For vaccine developers, the large mutation of the virus is certainly not good news, but on the other hand, it is also a sudden test of their technical capabilities. Ugur Shahin, CEO of German BioNTech, who jointly developed a vaccine with Pfizer, said that although the virus is constantly evolving, its key targets have not mutated. “In the past, every time the virus mutated, the company’s tests showed that the vaccine was still effective against the new virus.” He even said that, technically speaking, the company was able to produce a new vaccine against the virus variant within a few weeks. .

Pfizer is more “foresighted” and pointed out that the reason why the new coronavirus has continuously mutated over the past year is because it is an RNA virus, and the enzymes used for replication are prone to errors when replicating the virus. Therefore, when Pfizer is developing a vaccine Using messenger RNA technology, compared with traditional vaccine technology, after the virus has been mutated, if a virus strain that is not covered by the existing vaccine appears, Pfizer can change the RNA sequence in the vaccine to match the new virus.

But not all researchers are optimistic about the adaptability of vaccines to mutant viruses. In the United States, more than one expert in the field of biology has expressed concerns about mutated virus strains. Michael Vorobey, director of the Department of Ecology and Evolutionary Biology at the University of Arizona, publicly stated: “This is an urgent problem. Public health officials seem to downplay the possibility that the new crown vaccine may be ineffective.”

Virus mutation will not stop
According to data released by the US Centers for Disease Control and Prevention, the variant new coronavirus discovered in the United Kingdom has 17 differences in genetic material from the common new coronavirus. In this regard, Vorobey said: “I have not seen these differences anywhere else. The variant of the new coronavirus is very unusual.”

A more terrifying hidden danger has also aroused discussion in the scientific community. The vaccinations of millions of people may induce new mutations and adaptations of the virus to avoid or resist the immune response induced by the vaccine. An epidemiologist from Queen Mary’s College, University of London, UK, believes that mass vaccination will cause similar mutations to become more common. At present, independent variant viruses have appeared many times in the world, which shows that large-scale mutations are beneficial to viruses.

According to estimates by the scientific community, to minimize the chance of virus mutation, it is necessary to immunize about 60% of the world’s people during the next year to promote large-scale vaccination and reduce the number of confirmed cases during this period.

From the perspective of “herd immunity”, whether the vaccines currently available can effectively reduce asymptomatic infections is more critical.

According to the information provided by the U.S. Food and Drug Administration when applying for emergency authorization, the clinical data of Modena’s new crown vaccine shows that after the first shot and before the second shot, the vaccine can reduce asymptomatic by about 2/3 Infection, it is expected that the prevention efficiency will be higher after two injections of complete vaccination.

Under the vaccine race, this is a kind of pressure for other vaccine developers. After the results of each vaccine are announced and put on the market, the vaccine research and development plan is still in progress. Whether other vaccines can complete the task of reducing asymptomatic infections will also become a very important competition indicator.

High-income countries stock more than half of the world’s vaccines
It is an ideal state to immunize 60% of the world’s people within one year.

Since most of the new crown vaccines currently available require two doses, if they are to cover 60% to 80% of the world’s 7.8 billion population in order to achieve the so-called “herd immunity” effect, the total demand for vaccines in the world will exceed 10 billion doses. .

This will pose a great challenge to the production capacity of major pharmaceutical companies and the global supply chain. For those countries that secretly compete in the vaccine race, what is tested is the level of development of the vaccine industry, national financial resources and even diplomatic capabilities, as well as the production capacity and profits of the vaccine itself.

From the macro perspective of regional public epidemic prevention, the panic buying of vaccines by countries is both realistic and cruel. According to statistics, in this vaccine competition that reflects comprehensive national strength, high-income countries where 14% of the world’s population are located have ordered 53% of all promising new crown vaccine production.

On December 29, 2020, Athens, Greece, the new crown vaccine was delivered to Venizelos International Airport

In the United Kingdom, which is the first in the West to start large-scale immunization of the new crown vaccine, 40 million doses of the vaccine were ordered from Pfizer and 100 million doses of the Oxford/AstraZeneca vaccine, which is about to end clinical trials. And all the new crown candidate vaccines currently ordered by the EU can guarantee up to nearly 2 billion doses of vaccines for the member states if they are all approved.

Public information shows that the United States has ordered a total of 200 million doses of new crown vaccines, half of which are from Pfizer and the other half from Modena. Modena also recently allowed the United States to order another 400 million doses of vaccine, which means that the United States can ensure at least 600 million doses of vaccine supply.

In contrast, it is predicted that in 67 low- and middle-income countries, only 1 in 10 people can get the new crown vaccine before the end of 2021.

Vaccines have different effects
The overall effect of the new crown vaccine research and development is higher than expected, but judging from the vaccine effectiveness data of the completion of the third phase of clinical trials, the differences between the vaccines are relatively obvious.

The effectiveness data published by the messenger RNA nucleic acid vaccine is the most eye-catching. The vaccine jointly developed by Pfizer and BioNTech has an effective protection rate of 95%, while that of Modena’s vaccine has 94.1%.

However, due to the instability of RNA molecules, the storage and transportation conditions of messenger RNA nucleic acid vaccines are more stringent than other vaccines. Pfizer vaccine can be stored for 6 months in a constant temperature environment of minus 70 degrees Celsius, but it can only be stored for 5 days at 2-8 degrees Celsius.

The production cost of adenovirus vector vaccine is relatively not so high, and it is more likely to be produced on a large scale in developing countries and regions. The comprehensive effectiveness of AstraZeneca’s adenovirus vaccine is 70%, and its safety remains to be verified. Although the vaccine’s Phase III clinical trial data is controversial, it is still in the first echelon of the market.

Why is the Phase III clinical trial critical? After the vaccine has undergone early research, preclinical research, phase I and phase II clinical trials, when it reaches phase III clinical trials, it is necessary to observe the protective efficiency and protection efficiency of the vaccine for a long time in a real environment where the disease is prevalent and in a large population. safety.

In previous vaccine research and development, this phase of testing usually took years. It took less than a year for the new crown vaccine to complete the process from research and development to the market, which really made the public mixed.

The principle of the development of inactivated vaccines is that after culturing and isolating infectious viruses in the laboratory, they are killed by chemical methods to eliminate pathogenicity and retain antigenicity. “Specially made” viruses are injected into the human body, which can stimulate the immune system of healthy people and achieve the ultimate goal of producing antibodies to the new coronavirus.

However, the production of this “special” virus or vaccine antigen has very high requirements for the production environment, and it needs to be cultivated in a biosafety protection level three (P3) laboratory, which restricts large-scale production. There are public reports that when domestic inactivated vaccines were being developed in the early stages, some pharmaceutical companies had to go to the National Center for Disease Control and Prevention to produce vaccines due to the lack of a P3 laboratory production environment.

The production of recombinant subunit vaccines does not require a complete virus, has higher safety, is easy to produce on a large scale, and has a lower cost, but it is too early to go on the market. At the end of December 2020, a research and development unit will start a key phase III clinical trial for this vaccine worldwide.