There is a new way to take the vaccine now, without the involvement of any needles. So, how do these vaccines work?
Last Friday, the Drug Controller General of India (DGCI) granted emergency use approval to ZyCoV-D, which is Zydus Cadila’s needle-free vaccine. This is the world’s first DNA based vaccine against the SARS-COV-2 virus, and the sixth COVID-19 vaccine to be approved in India. India already has Bharat Biotech’s Covaxin, Oxford-Astrazeneca’s Covishield, Russia-made Sputnik V, Moderna vaccine, and Johnson & Johnson’s Janssen vaccine, which have received approval for the Emergency Use Authorisation (EUA).
The Vaccine
The ZyCov-D vaccine utilises a needle-free method called Tropis, which is designed by an American company called Pharmajet. The method uses a “single-use, sterile, disposable syringe used with a reusable injector”. This method reduces the risk of cross contamination and eliminates the issue of needle injury.
The vaccine is also known as the third-generation vaccine. These vaccines use engineered DNA to induce an immune response against the virus. This “radical new approach” provides several advantages over traditional vaccines, including “improved vaccine stability, the absence of any infectious agent and the relative ease of large-scale manufacture”, according to the World Health Organisation.
The Differences
Vaccines made by Pfizer-BioNTech and Moderna are mRNA vaccines. The difference between the DNA and RNA vaccines is they are transmitted to another molecule that is called messenger RNA. Also, the DNA vaccine delivers the message through a small electric pulse that pushes the message to the cell.
Dr. Shreoshi Saha, ESIC Hospital told the Financial Express, “Classic DNA vaccine when administered, after entering the body, it converts into RNA and mimics viral RNA structure and induces host immunogenicity while the mRNA vaccines are administered in viral genetic material form i.e. RNA itself. So basically mRNA vaccines are one step ahead of DNA vaccines. However, main human genetic material is DNA making DNA VACCINES safer to administer whereas mRNA vaccines may not be acceptable by host defense being foreign genome.”
Efficacy & More
Unlike the other COVID-19 vaccines that are currently being given in the nation, ZyCOV-D is a three-dose vaccine. According to the company, the three doses should be administered on day 0, day 28, and day 56.
The interim analysis from Phase 3 clinical trials showed that, in more than 28,000 volunteers, Zydus Cadila’s COVID-19 vaccine has shown an efficacy rate of 66.6% for symptomatic RT-PCR positive case. After the third dose, it was noted that no moderate case of COVID-19 was seen in vaccine beneficiaries. On the other hand, the data from the phase three trial is not peer-reviewed yet.
Zooming Out
Even though the concept of needleless vaccine is not completely new, a needleless COVID-19 vaccine is a welcoming creation because it reduces the risk of cross contamination. Also, ZyCOV-D is the first vaccine candidate found to be eligible for the use for children above the age of 12. Hence, it is needle-free, administering the dose to the kids would be much easier than administering the vaccine through a needle.
The manufacturers have said that the vaccine will be made available within 45 to 60 days after getting the authorisation. So, India is adding one more vaccine to its arsenal, and the quicker we vaccinate our citizens, the better chance we have in avoiding the prolonging of this pandemic.
