India is preparing to fight Covid-19 with the world’s first human DNA vaccine. ZyCoV-D, its distribution Urgently approved by Indian health authorities on August 20th, should be administered to the population in September.

A vaccination campaign that is closely monitored because DNA vaccine technology, like that with messenger RNA from Pfizer or Moderna, is seen as a hope for the treatment or protection against a variety of serious diseases.

66% effective

ZyCoV-D is coming to bolster the country’s vaccine arsenal – in addition to AstraZeneca, India’s Covaxin, and Russian Sputnik V – at a time when India is beginning to Looking towards the end of a year with disastrous health. The number of new infections has increased from more than 400,000 daily infections in May to around 40,000 a day, and the number of deaths has also been divided by ten from the height of the epidemic.

The devastation of the second wave of Covid-19 in India, which can also be attributed to the famous Delta variant created there, has led New Delhi to dedicate as many resources as possible to the development of local vaccines. And ZyCoV-D is the most important example of this.

It was found to be 66% effective at protecting against severe forms of Covid-19, Indian pharmaceutical company Cadila Healthcare announced in the press release with the results of its clinical studies, which have been conducted on 28,000 participants since January. A rate that seems modest compared to the over 90% effectiveness of messenger RNA vaccines from Pfizer or Moderna. ZyCoV-D, however, was tested while the Delta variant was rampant while other vaccines were being developed when only the original strain of Sars-CoV-2, which is less resistant to vaccine treatments, was still being discussed, the pharmaceutical company recalls.

However, this first DNA vaccine will not escape comparison with its messenger RNA cousins, since “it is the closest to it in terms of its functionality,” emphasizes Al Edwards, immunologist and specialist. contacted by France 24.

>> Read also: “Messenger RNA, the innovative technology behind the vaccines from Pfizer and Moderna”

These two vaccine families each use a piece of RNA or synthetic DNA that “contains instructions for the body to make the famous spike protein of the Sars CoV-2 virus so that the immune system can develop antibodies,” explains Pierre. Saliou, Associate Professor of Val-de-Grâce and specialist in vaccinology, contacted by France 24.

Cheaper and easier to store

The big difference is that the piece of synthetic DNA “has to be injected deep into the cell nucleus in order to be deciphered, while the messenger RNA can remain on the cell surface,” summarizes Al Edwards.

The road ahead is therefore longer and more complicated, and this is the main reason why no DNA vaccine has yet been shown to be effective in humans. However, some were designed for animals, including a vaccine that protects horses from the West Nile virus.

ZyCoV-D must also be administered three times, unlike most other vaccines, which are expected to take full effect after a maximum of two injections.

DNA vaccines therefore seem to be more complex to develop and at the same time offer potentially poorer protection against Covid-19 than messenger RNA vaccines. So why not go for the latter? In fact, eleven other DNA vaccines are still in development, according to the list of the World Health Organization (WHO).

First, betting on DNA seemed more promising. “About a year and a half to two years ago [c’est-à-dire au début de la pandémie], we weren’t even sure if messenger RNA vaccines could work while laboratory work done for at least twenty years has shown the feasibility of DNA vaccines, “said Al Edwards of the University of Reading.

ZyCoV-D et al. also pose a much smaller logistical challenge than messenger RNA vaccines. They can be stored at temperatures between -2 ° C and 8 ° C for several months, while messenger RNA vaccines should be stored in freezers at much lower temperatures. “This is because DNA is extremely stable, while RNA strands are particularly fragile,” explains Pierre Saliou.

That may also make them cheaper. “You don’t have to pay for specific storage solutions,” says Al Edwards. Easier to transport and store, and less expensive to use, these vaccines could be an ideal solution for developing countries.

Additionally, a small bonus for belonephobe (the fear of needles), the ZyCoV-D does not require a prick as it is administered through a needleless injection system.

Where is the science?

These DNA vaccines share a central trait with those with RNA, who in the scientific community say these are the vaccine technologies of the future: they are very adaptable. The same technological platform that made it possible to develop the first DNA vaccine against Covid-19 can now be used to develop molecules to fight other diseases. Such vaccines are also currently being tested. against the Zika virus (mosquito bite-borne disease) or against HIV.

But it can still be a little early to get the win. ZyCoV-D certainly seems to have convinced Indian health authorities, but scientists do but would like to know why. Cadila Healthcare’s laboratory has not released specific data to scientifically support the claims made in the press release.

“ZyCoV-D is potentially a very good vaccine, but the lack of transparency is worrying,” Jammi Nagaraj Rao, an Indian immunologist, writes in a column published by the Indian news site The Wire. “Indian biotech companies have the know-how to make medical breakthroughs the size of a first DNA vaccine, but it is clear that having full scientific data would be more reassuring,” admits Al Edwards.

Therefore, the continuation of the vaccination campaign in India, where only 17% of the population is fully vaccinated, is being monitored very closely. This will be the first comprehensive test for a whole new family of vaccines. For Al Edwards, “we must never forget that before this virus emerged, there was a shortage of vaccine tools and this pandemic made it possible to demonstrate the medical validity of innovative technologies” and which could make a difference across borders Sars-CoV-2 Pandemic.