Vaccines made on the mRNA platform have so far been found to be among the most effective against the novel coronavirus. Shots produced by the US-based Pfizer and Moderna have been the mainstays of Covid-19 inoculation campaigns in advanced countries although this is the first time that vaccines built on this platform have been launched for public use. Now, India has taken another step towards having its own homegrown RNA vaccine after the Pune-based Gennova Pharmaceuticals said it is ready with Phase-I trial data. Although it’s still early days for this vaccine under development, here’s all you need to know about the newest shot that India can look forward to.
What Is The Gennova Vaccine?
Known as HGC019, the vaccine is the result of a collaboration between Gennova and the US-based HDT Biotech Corporation. The company said it started work on the vaccine right after the Sars-CoV-2 genome was published — in January 2020 — and that the vaccine “has already demonstrated safety, immunogenicity, neutralisation antibody activity in the rodent and non-human primate models".
According to a filing on the clinical trials registry maintained by the Indian Council of Medical Research (ICMR), the Phase-I trial involved “a randomised, open-label, placebo-controlled, multi-centre study to assess the safety and immunogenicity of HGCO19 vaccine" and enrolled 120 healthy participants in the age group of 18-70 years. The New York Times said the company got the nod to hold combined phase trials and the Phase-II trials feature “approximately 500 healthy subjects in the age group of 18 to 75 years".
Animal trials of the vaccine showed that its “neutralising antibody response… was comparable" with antibody levels measured in patients recovering from Covid-19.
Four vaccines have already been okayed for use in India: Covishield, Covaxin, Sputnik V and Moderna.
What Are mRNA Vaccines?
These vaccines belong to the category of nucleic acid vaccines, which use genetic material from a disease-causing virus or pathogen to trigger an immune response against it within the body.
All vaccines seek to expose the body to the active part of the pathogen that enables it to infect humans so that the immune system recognises it and produces antibodies against it in the future. How traditional vaccines achieve this is by inserting a part of the virus itself — either
weakened or inactivated — into the body. But what nucleic acid vaccines, like DNA or RNA vaccines, do is to insert the genetic code of the pathogen into the body to prompt the human cells themselves to produce the target proteins for the immune system to identify and attack.
Since such vaccines do not use any live components of the virus, they are seen as posing no risk of actually triggering the disease. Further, these vaccines are also relatively easy to produce as the key factor is to have sequenced the genome of the target pathogen. The Moderna mRNA vaccine had gone into clinical trials within two months of the SARS-CoV-2 genome being sequenced.
But this approach to creating vaccine is “relatively new" and while DNA and RNA vaccines are being developed against various diseases, including HIV, Zika virus, it is with Covid-19 that the first such vaccines have been authorised for human use after they received emergency clearance from drugs regulators.
What Is The USP Of The Gennova Vaccine?
Gennova said that the spike protein its vaccine is working with expresses the D614G mutation of the novel coronavirus, which was one of the earlier prominent strains to spread across the world. Indeed, most vaccines being used now were designed at a time when none of the strains now prevalent were around although tests have shown that full vaccination with the available shots provides safety against those.
Gennova also added that its HGCO19 vaccine uses the self-amplifying saRNA platform, which means it is slightly different from the likes of the Pfizer and Moderna vaccines, which are built on the mRNA platform. While both mRNA and saRNA vaccines work primarily by carrying the instruction, or message, to the human cells to produce the key protein of the target pathogen, an saRNA vaccine “also contains the code for the virus enzyme", which enables it to “create multiple copies of the virus RNA once it’s in our cells, leading to quicker protein production".
Since an saRNA vaccine can produce copies of itself inside a cell, “lower doses are required than those for mRNA vaccines" and the cost per per dose is also lower with the same volume of vaccine producing more doses. Studies have found that “equivalent levels of protection were achieved using 1.25mg saRNA based on data from vaccines tested in animal models for other viral diseases compared to 50‑250μg for mRNA2 for Covid-19".
It has been reported that Gennova’s HGCO19 “has lower dosing requirements as it uses the self-amplifying mRNA platform".
When Will The Vaccine Be Ready For Rollout?
The vaccine makers are set to submit only the Phase-I clinical trial data and there is still some ways to go before the shot can be ready for production. Company officials have been quoted in the media as saying that “in the next step, we will get permission for combined Phase II and III trials… and then apply for Emergency Use Authorisation".
The company said it’s augmenting its “capacity, supply chain, investments and distribution" and noted that the vaccine can be stored at temperatures of 2-8 degrees Celsius, which means the logistics for its transportation may not present any significant problems.