Zydus Cadila's vaccine for children who are 12 years and above has an efficacy rate of 66%-67% among adults and 100% efficacy among children to date, says managing director Dr Sharvil Patel. The vaccine is due for launch next month.
"As of now, the interim efficacy for adults stands at 66-67%. For children, currently, the efficacy is 100%, but it’s not the way to look at it. You do a safety and immunogenicity study because you see higher antibodies in children, you will see the same efficacy as the hope. Maybe better, because Children have a better immune response,” Patel tells Fortune India.
The trial was conducted in over 28,000 healthy adults—1400 of those were kids above 12 years of age. No case has been reported among the kids, taking their efficacy to 100%.
In vaccine delivery, children will be prioritised since there is no vaccine for them yet. It will also be the world's first needle-free vaccine; the world’s first Plasmid DNA Vaccine for COVID-19. ZyCoV-D will be administered in three doses—zero, on the 28th day and the 56th day. For children, the dose is the same, though the company is also working towards a two-dose regimen.
Zydus already supplies vaccines for basic programmes such as Diphtheria, Pertussis, Tetanus, Haemophilus Influenzae type B, Hepatitis B, Measles, Mumps, Rubella, Varicella, Influenza and Typhoid fever. In addition, VTC is developing new vaccines such as Human Papilloma Virus, Leishmaniasis, Malaria, Haemorrhagic Congo Fever, Ebola and Japanese Encephalitis. Its rabies vaccine manufacturing facility has received WHO pre-qualification and is one of the largest rabies manufacturing facilities in India.
ZyCov-D uses circular strands of DNA to prime the immune system against the virus SARS-CoV-2, whereas Covaxin uses an inactivated virus; Covishield uses chimpanzee adenovirus (AZD1222 or ChAdOx1), which carries the SARS-CoV-2 spike protein.
With this approval, India now has its first COVID-19 vaccine for adolescents and is the first DNA-based vaccine to receive EUA in the world, though there are others hot on its heels. It is to be administered for the 12-18 age group, besides the adult population. ZyCoV-D is a needle-free vaccine administered using The PharmaJet—a needle-free applicator, which ensures painless intradermal vaccine delivery. “DNA based vaccine has to go through the skin,” says Sharvil Patel.
This is for the first time that a technologically advanced vaccine has been successfully developed on the Plasmid DNA platform for human use in India. Even though recombinant technology—both for DNA and mRNA have been around—the choice to go for DNA as a platform was based on several factors, “Stabilising the RNA is a challenge and the cost associated with manufacturing something to scale and magnitude had to be considered. When we looked at DNA, it was a well-established area, Mers SARs had used DNA based technology, and both the World Health Organisation (WHO) and U.S. Food and Drug Administration (FDA) had significantly updated their guidelines,” says Patel. "All the safety-related parameters had been addressed, so there were very few concerns of safety, as far as regulatory authority was concerned for this platform. In vaccine development, the first concern is safety, because you are vaccinating many people. Safety signals are even more critical than efficacy."
Secondly, with it being the coronavirus, the scientific team at Zydus had to account for frequent mutations. “It is in the nature of the virus, so we needed a platform which could adapt to the mutation. So, with Plasmid DNA, it was plug and play. All you have to do is update the gene sequence without changing anything else and its efficacy, development or manufacturing remains the same,” says Patel.
Another consideration was that stabilising the DNA based vaccine is easier at 2-8 degrees. It is much more suitable to our environment. mRNA-based platforms require a superior cold chain. A big factor for Zydus was that the lipids etc. required would have to be internationally sourced, so using DNA had a big advantage. It is given through a needle-free application and that is the only way DNA inject—intra-dermal application and needle-free.
Keeping track of international developments, DNA based vaccines have shown minimal side effects, so there is no fever or pain as DNA does not have vector bound immunity so no spikes in temperature. The Zydus team is upbeat. They also have just launched the flu vaccine—the tetravalent VaxiFlu 4—which encouraged them to go ahead with developing an entirely new product.