India’s drug regulator on Sunday gave its final approval to the Oxford-AstraZeneca and Bharat Biotech coronavirus vaccines for restricted use in an emergency situation, giving the country its first two shots for immunising its vast population in the coming weeks.
While the Oxford-AstraZeneca vaccine, manufactured by Serum Institute of India (SII), has 70.42 per cent efficacy, the indigenous vaccine from Bharat Biotech does not have efficacy details because the trials are underway. It is doing a study of 25,800 volunteers and around 22,500 participants have been given at least one jab.
Both vaccines can be stored at 2-8 degrees Celsius and the companies have been stockpiling them for dispatch once the approvals come.
SII has a stockpile of over 50 million doses at the moment and can make 100 million doses per month.
“After an adequate examination, the Central Drugs Standard Control Organisation (CDSCO) has decided to accept the recommendations of the subject expert committee,” said V G Somani, drug controller general of India (DCGI).
While in the short press briefing the DCGI did not take any questions, he said the data from Phase 3 trials in India had shown Bharat Biotech’s Covaxin to be “safe” (according to the data available to date).
Covaxin, however, may be used as a “back-up” vaccine, while the data from ongoing trials is being generated.
India’s drug regulator has allowed restricted use of Covaxin in an emergency situation.
Efficacy data is unblinded once a critical number of Covid-19 positive cases appears in the sample population where some people have received a placebo shot, while others have been given the vaccine. Once a certain number of Covid-19 positive cases happens, the investigators unblind the data to analyse the efficacy of the vaccine in preventing the disease. Therefore, it would take some more time for the data to be generated and the company will have to share it with the regulator on a rolling basis.
Sources in the expert panel indicated some interim data was shared with them for the review.
Meanwhile, SII, which is developing Covishield, the Oxford vaccine, had sought emergency approval for its vaccine on the basis of the interim safety and immunogenicity data from the Phase 2 and 3 trials, conducted on 1,600 participants in the country, along with the findings of overseas clinical studies done on 23,745 participants. The overall vaccine efficacy was found to be 70.42 per cent.
An upbeat Adar Poonawalla, chief executive officer, SII, said in a tweet, “Happy New Year, everyone! All the risks @SerumInstIndia took with stockpiling the vaccine, have finally paid off. Covishield, India’s first Covid-19 vaccine, is approved, safe, effective and ready to roll out in the coming weeks.”
Bharat Biotech’s Covaxin a back-up
The reason why India decided to approve the under-trial Bharat Biotech vaccine is that it is based on a whole inactivated virus platform. Bharat Biotech said the evaluation of Covaxin had resulted in several “unique product characteristics”, including a long-term persistence of immune responses to multiple viral proteins as distinct from only the spike protein, and has also demonstrated broad spectrum-neutralising capabilities with heterogeneous Sars-CoV-2 strains.
“It has also shown to generate memory T cell responses … indicating longevity and a rapid antibody response to future infections. Its most critical characteristic is the demonstrated safety profile, which is significantly lower than several other vaccines with published data,” Bharat Biotech further added.
The company said it had submitted all data (generated so far) to the regulator. Speaking to a television channel, Randeep Guleria, director of the All India Institute of Medical Sciences, New Delhi, said Covaxin could be kept as a “back-up”. In case an approved vaccine showed any decline in efficacy because of a variant strain, one will have a whole virus-inactivated vaccine as a back-up. Theoretically at least, a whole inactivated virus vaccine is expected to generate an immune response against variant strains.
Krishna Ella, chairman and managing director, Bharat Biotech, thanked Indian Council of Medical Research (ICMR) Director-General Balram Bhargava for his “visionary leadership” in this project and said this was a public-private partnership between Bharat Biotech, National Institute of Virology (NIV), and the ICMR.
How are the two vaccines different?
Covaxin is based on a highly purified and inactivated two-dose Sars-Cov-2 vaccine manufactured in a vero cell manufacturing platform. The company claims this platform has an “excellent safety track record” of more than 300 million doses. It is the traditional vaccine technology that uses an inactivated virus to prime our immune response against the pathogen. The advantage is that it is time-tested, and when a whole virus is used, theoretically it should induce an immune response for variant strains. However, we do not know the efficacy of Covaxin yet.
The Oxford-AstraZeneca vaccine, on the other hand, uses a chimpanzee adenovirus (common cold virus) to deliver the genetic material of a pathogen into cells. This creates an immune response against the Sars-CoV-2 virus.
Bharat Biotech added Covaxin had been evaluated in approximately 1,000 subjects in the Phase 1 and Phase 2 clinical trials and the data has been accepted in international peer-reviewed scientific journals. The vaccine is now in the middle of a 26,000 volunteer Phase 3 efficacy study, the largest such trial ever conducted for any vaccine in India.
The run-up to the approvals
The expert panel consisting of domain knowledge experts in pulmonology, immunology, microbiology, pharmacology, paediatrics, and internal medicine had met on Friday and Saturday to analyse the data given by SII and Bharat Biotech to make its recommendations in favour of granting the restricted use approval to both vaccines.
Poonam Khetrapal Singh, regional director (Southeast Asia), World Health Organization, in a statement issued soon after the DCGI announcement, said: “This decision will help intensify and strengthen the fight against Covid-19 pandemic in the region. The use of vaccine in prioritised populations, along with continued implementation of other public health measures and community participation, will be important in reducing the impact of Covid-19.”
India is planning to inoculate 300 million people in the first tranche of vaccination. That includes health care workers, front line workers, and those above 50 and those with comorbidities.