COVAXIN
EVERY CLOUD HAS A SILVER LINING!
India has exceeded 140 tests per day per million population as advised by the World Health Organisation by nearly 6 times. India’s Covid-19 Tally Crosses 66 Lakh-mark With Spike of 74,442 New Cases in 24 Hrs.
WHAT IS COVAXIN?
The vaccine candidate was developed by Bharat Biotech India Limited (BBIL) in collaboration with the National Institute of Virology (NIV). The indigenous, inactivated vaccine is developed and manufactured in Bharat Biotech’s BSL-3 (Bio-Safety Level 3) high containment facility. NIV isolated a strain of the novel coronavirus from an asymptomatic Covid-19 patient and transferred it to BBIL early in May. The firm then used it to work on developing an “inactivated” vaccine — a vaccine that uses the dead virus — at its high-containment facility in Hyderabad. “Once the vaccine is injected into a human, it has no potential to infect or replicate, since it is a killed virus. It just serves to the immune system as a dead virus and mounts an antibody response towards the virus,” said the company, adding that inactivated vaccines usually have a proven safety record. Covaxin then underwent pre-clinical testing on animals such as guinea pigs and mice to see if it is safe before the firm approached CDSCO for approval to move on to human trials. The first phase, usually conducted on a small group, tries to find what dosage of the vaccine is safe for use, whether it is effective in building their immunity to the virus, and whether there are side effects. The second phase is conducted on a group of hundreds of persons fitting the description of those for whom the vaccine is intended, using characteristics like age and sex. This phase tests how effective the vaccine is on the population group being studied.
WHAT ARE THE STAGES OF DEVELOPMENT CYCLE OF A VACCINE?
According to CDC, the general stages of the development cycle of a vaccine are:
Exploratory stage
Pre-clinical stage
Clinical development
Regulatory review and approval
Manufacturing
Quality control
WHATS THE CURRENT STATUS?
The vaccine received DCGI approval for Phase I & II Human Clinical Trials and the trials were commenced across India from July, 2020. Bharat Biotech is currently conducting phase 2 human trials of COVAXIN after receiving approval from the Drug Controller General of India (DCGI).
According to a news report, Indian biotechnology company Bharat Biotech has announced its novel coronavirus vaccine COVAXIN approved for human trials, will use adjuvant Alhydroxiquim-II to boost immune response and longer-lasting immunity. The technology is being used under this licensing agreement with Kansas-based ViroVax LLC, the vaccine innovator said in a press release on Monday.
ADJUVANT FOR LONG TERM IMMUNITY
There is a critical need for development and availability of adjuvants that elucidate mechanisms of action inducing greater antibody responses to vaccine antigens, thus resulting in long-term protection against pathogens. Adjuvants also enhance the sustainability of the global vaccine supply on account of their antigen-sparing effect. The widely used adjuvant Aluminium hydroxide in the development of SARS CoV-2 vaccines is known to induce a Th2 based response (which are important for the eradication of extracellular parasites and bacterial infection). The Th2 based response has a theoretical risk of vaccine-associated enhanced respiratory diseases (VAERD or ADE). Imidazoquinoline class of adjuvants (TLR7/8 agonists) is being used, which are known to induce Th1 based response which further reduces the risk of ADE (Anti-Body Dependent Enhancement). In preclinical studies and animal challenge models (Syrian Hamster and Rhesus Macaques), it has been shown that COVAXIN induced Th1 based response due to the use of Algel-IMDG (chemosorbed imidazoquinoline onto the aluminum hydroxide gel) as an adjuvant.
WHY BLOOD FROM A NEWBORN CATTLE IS USED?
In a research paper recently released by the Indian Council of Medical Research and Bharat Biotech about Covaxin, the Covid-19 vaccine they are developing, scientists have mentioned that one of the ingredients used is blood serum from newborn cattle. Covaxin falls in the category of inactivated vaccines, in which the pathogen is deactivated so that it can no longer cause infection. However, parts of the virus can still be identified by the body’s immune system, triggering a reaction. To produce the vaccine, vero CCL-81 cells — a line of cells from the kidney of a normal adult African green monkey — are grown in the lab. These cells are then exposed to the SARS-CoV-2 virus in bioreactors under controlled conditions. The virus is then harvested after about 36 hours and inactivated.The inactivated virus is mixed with adjuvants — substances known to enhance immune response. In the case of Covaxin, the adjuvants used are alum and a molecule known as imidazoquinoline, which helps the body better recognise RNA from viruses.To grow cells in the lab, scientists need to provide conditions that allow cells to divide and turn into specific cell types required for their experiments.For Covaxin, scientists used Dulbecco’s Modified Eagle Medium (DMEM), along with 5–10 per cent newborn calf serum. DMEM contains several essential nutrients required for cell division.
Bharat Biotech, ICMR and National Institute of Virology, Pune (NIV) backed Covaxin is making steady progress and winning praise from proud Indians. According to chief investigators monitoring the phase II trials of the vaccine, the candidate is able to deliver strong immunogenicity response and delivers low, or no side-effects. If all goes well, phase III of the vaccine would be started soon pan India, beginning in Lucknow.
