May 30, 2024

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Indian COVID-19 DNA vaccine: The efficiency of the Delta variant is 67%

InIndian COVID-19 DNA vaccine: The efficiency of the Delta variant is 67%


Indian COVID-19 DNA vaccine: The efficiency of the Delta variant is 67%.  The efficiency of the Delta strain is 67%. Will the Indian DNA vaccine be a “dark horse”



DNA vaccine is easy to produce nd easy to store and transport


The delta mutant strain has caused multiple rounds of epidemics in many countries, and it has spread to more than 150 countries around the world.


India, as the country where the delta mutant was first discovered, suffered the madness and baptism of delta.


For a time, hospitals and crematoriums were overwhelmed. Recently, although the epidemic situation in India has eased compared to the second peak, it is still not optimistic.

At present, the total number of confirmed cases exceeds 33 million, and the death toll exceeds 440,000. On September 14th, there were more than 27,000 newly confirmed cases in a single day.

In this situation, a DNA Covid-19 vaccine (ZyCoV-D) recently approved by the Indian drug regulatory agency may bring a glimmer of light to it.

According to a report in Nature on September 2, this is the world’s first DNA coronavirus vaccine approved for use in humans. In a large-scale clinical trial targeting more than 28,000 people, the effectiveness of this vaccine reached 67%, and India may start using this vaccine this month.



Effective for “Delta variants”


According to a report in “Nature” magazine, recently, India urgently authorized the approval of a new DNA coronavirus vaccine-ZyCoV-D.


One of the highlights of this DNA vaccine is that by pressing a needle-free device on the skin, the tiny high-pressure liquid stream generated by the device pierces the surface of the skin and delivers the drug to the subcutaneous tissue rich in immune cells. This method not only avoids the pain caused by the injection, but also captures the DNA particles of the vaccine more effectively.


How does the DNA vaccine work? To put it simply, the DNA vaccine contains circular DNA (also called a plasmid) that encodes the information of the new coronavirus spike protein (S protein).

After the plasmid enters the nucleus, it is first transcribed into mRNA, and then the mRNA reaches the cytoplasm, where it is translated into spikes. Protein, activates the human immune system.

Usually, the plasmid is degraded within a few weeks to several months after entering the human body.


This vaccine was developed by the Indian pharmaceutical company Zydus Cadila. Zydus Cadila said that the vaccine may start to be used this month and is expected to reach a production capacity of 50 million doses early next year.


According to a report by BusinessLine in July, Zydus Cadila announced the interim results of a phase III clinical trial conducted among more than 28,000 volunteers (12-99 years old), showing that the effective rate of vaccinated patients infected with the COVID-19 virus after three doses of vaccination 66.6%.


It is worth noting that the Phase III clinical trial of the vaccine was carried out during the second wave of the epidemic in India. At that time, the delta variant was the main prevalence in India.


Dr. Sharvil Patel, managing director of the aforementioned company, believes that because the trial was conducted during the peak period of infection (April to June), the vaccine is also considered effective against the variant. According to the serum survey, 99% of infections come from the delta variant. He pointed out that this vaccine should be modified to deal with new variants of concern.


Delta mutant strains are still the mainstream dominant strains worldwide. Since it was first discovered in India in October last year, it has now spread to more than 150 countries around the world.


Jin Dongyan, a professor at the School of Biomedicine , School of Medicine, University of Hong Kong , said in an interview with China News Weekly that from the perspective of the protection rate, the value of 67% is not high. He believes that DNA vaccines have not been used on humans in history, and this is a new path for Indian scientists.

Four DNA vaccines previously used in animals have been successful, so in theory, this DNA vaccine should also be successful.


“However, from the perspective of its product attributes, DNA vaccines may not occupy too much market share in the future.” Jin Dongyan said.

Virologist Shahid Jameel of Ashoka University in India pointed out that although the DNA vaccine seems to be less effective than some mRNA vaccines, these data are not comparable.

He said that in the clinical trials conducted in India earlier this year, the delta mutant strain was the main epidemic strain, and the early clinical trials of mRNA vaccines were conducted when the lower-transmissible mutant strains were circulating. The 67% protective effect of this vaccine is actually against the delta variant, so it is quite good.


However, at present, Zydus Cadila has not announced the results of the late-stage clinical trials of the vaccine. Some researchers questioned this, saying that India lacked transparency in the process of approving this vaccine. The company said that related trials are still in progress and a complete analysis report will be submitted shortly.

With Delta still raging, this DNA vaccine was approved for emergency authorization in India. Can it bring a turning point for the epidemic? According to Jin Dongyan’s analysis, India’s current natural infection rate is already very high, and the new vaccine is no longer the main means to solve its current epidemic. It is important to get intensive injections as soon as possible.



Is it better than mRNA vaccine?

Nucleic acid vaccines include RNA vaccines and DNA vaccines.  In fact, DNA and mRNA vaccines have been under development since the 1990s. Under the “ripening” of the COVID-19 epidemic, mRNA vaccines have made a series of rapid progress, but DNA vaccines have been difficult to achieve major breakthroughs.

Shahid Jameel believes that the main challenge for DNA vaccines is that they need to reach the nucleus to work, while mRNA vaccines only need to reach the cytoplasm. Therefore, DNA vaccines have been difficult to induce effective immune responses in clinical trials for a long time. This is why DNA vaccines have only been approved for use in animals so far.

However, DNA vaccines have their unique advantages. According to reports, the DNA Covid-19 vaccine approved in India can be stored at 25°C for at least 3 months, with an annual output of up to 120 million doses. The researchers pointed out that DNA vaccines are easy to produce, and the finished product is more stable than mRNA vaccines, which usually need to be stored at very low temperatures.

Shahid Jameel said that if DNA vaccines prove to be successful, this is undoubtedly the future of vaccinology, because DNA vaccines are easy to produce.


The same is a nucleic acid vaccine, will a DNA vaccine be better than an mRNA vaccine?


The biggest advantage of DNA vaccines lies in their low cost. However, mRNA vaccines are still more advantageous and competitive than DNA vaccines.

He further explained that DNA vaccines are actually equivalent to the previous generation of mRNA vaccines. Both have similar advantages, but DNA vaccines also have some disadvantages that mRNA vaccines do not have. For example, it may be integrated into cells, and the protection efficiency is not as high as that of mRNA vaccines. Therefore, DNA vaccines are unlikely to become mainstream vaccines in the future.

A postdoctoral researcher at Cornell University School of Medicine, told media that, similar to mRNA vaccines, DNA vaccines also use the vaccinator’s own human cells as a “factory” to efficiently express viral proteins to induce immune responses.

He believes that compared with mRNA vaccines, DNA vaccines have the advantages of being more stable at room temperature, easy to store and transport. However, the current protection of DNA vaccines is better than that of mRNA vaccines, which still needs to be further verified.

Vaccine expert Tao Lina said that the immune and protective effects of this generation of DNA vaccines seem to be comparable to inactivated vaccines, but not as good as mRNA vaccines.

In addition, the long-term safety of DNA vaccines has received attention.

If the DNA in the vaccine is integrated into the human DNA, it may lead to the continuous expression of the target antigen. The long-term effect of this antigen repeatedly stimulating the immune system is still unclear.

Since DNA is human genetic material, foreign DNA theoretically has the possibility of being integrated into the human cell genome and causing mutations. The related safety hazards of DNA vaccines also urgently require research and investigation.

It is worth noting that the global development of DNA vaccines is constantly advancing.

According to the latest statistics of the WHO, there are 27 new coronavirus DNA vaccines in the world under development, 11 of which have entered the clinical stage, and more than 6 are in the early stage of testing.

In addition to ZyCoV-D, which has been approved for emergency use, two DNA vaccines have entered the later stage of testing. One is jointly developed by Inovio Pharmaceuticals in the United States and the Chinese pharmaceutical company Ai Di Weixin, and the other is in charge of the Japanese company AnGes. Among them, the DNA COVID-19 vaccine (INO-4800/pGX9501) jointly developed by Inovio Pharmaceuticals and Ai Di Weixin has attracted more attention.

As early as February last year, Kangtai Bio (300601.SZ) announced that the company and Ai Diweixin signed a “strategic cooperation agreement”, intending to use their respective advantages to jointly develop a COVID-19 DNA vaccine.

Some analysts believe that Inovio Pharmaceuticals has experience in developing DNA COVID-19 vaccines, Ai Di Weixin has very good research and development capabilities in nucleic acid vaccines and supporting adjuvants, and Kangtai Biosciences has the strength in vaccine preclinical, clinical research, and subsequent industrialization. Stronger, this can be seen as a strong alliance.

According to reports, Inovio Pharmaceuticals has planned to conduct initial trials of DNA vaccines in Asia, South America and Africa. The company recently stated that it has been authorized by the Brazilian regulatory agency and is expected to start a large-scale clinical trial of the DNA vaccine INO-4800 in Brazil in September. Ai Diweixin once said that the DNA COVID-19 vaccine cooperating with Inovio will complete phase III clinical trials within this year and is expected to be available to the public in the second half of the year.

On August 9, Ai Diweixin announced that its COVID-19 DNA vaccine candidate (INO-4800/pGX9501) has been approved to conduct clinical trials to explore sequential immunization strategies with inactivated vaccines. In the above-mentioned clinical trials, the inactivated vaccine that was combined with the DNA Covid-19 vaccine was Kerlafore developed by Beijing Kexing.

The trial is divided into two specifically, one is to explore the effect of boosting the immunity of healthy adults over the age of 18 with the inactivated COVID-19 vaccine, and the other is to vaccinate healthy adults and the elderly with different doses of DNA COVID-19 vaccine. Research on boosting immunity with inactivated vaccines.

From another point of view, the approval of the new DNA vaccine in India is also regarded as a signal by the industry. In addition to the DNA vaccine against the new coronavirus, more DNA vaccines against other diseases will emerge in the future. Currently, DNA vaccines against influenza, human papillomavirus, HIV, etc. are also being tested or developed.



Indian COVID-19 DNA vaccine: The efficiency of the Delta strain is 67%

(source:internet, reference only)

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