Bharat Biotech says Covaxin efficacy 81%
NEW DELHI: Covaxin, the first coronavirus vaccine developed in India, has an efficacy rate of 81%, its maker Bharat Biotech said while citing preliminary results from its Phase 3 clinical trials, an announcement that is likely to come as a shot in the arm for India’s vaccination drive.
The vaccine was approved for an emergency roll-out on January 16 before it was established to be effective in preventing Covid-19, but experts as well as authorities pointed to Phase 1 and 2 trials that showed that Covaxin was safe and produced an adequate immune response.
“Today is an important milestone in vaccine discovery, for science and our fight against coronavirus. With today’s results from our Phase 3 clinical trials, we have now reported data on our Covid-19 vaccine from Phase 1, 2, and 3 trials involving around 27,000 participants. Covaxin demonstrates high clinical efficacy trend against Covid-19 but also significant immunogenicity against the rapidly emerging variants,” said Krishna Ella, chairman and managing director, Bharat Biotech.
The results revealed on Wednesday — detailed data is yet to be released or peer-reviewed — are based on an interim analysis when 43 infections took place among the 25,800 people who were part of
the trials. Of these, 36 were among those given a placebo, while seven got the vaccine, translating to an efficacy rate of 80.6%, the company said.
Prime Minister Narendra Modi and Union health minister Harsh Vardhan both took Covaxin to build faith in the indigenous vaccine, which has met with severe hesitancy, particularly among health care workers, for want of the efficacy data.
Disaggregated data from Delhi, for example, showed in January that turnout at locations administering Covaxin was as low as 25%, while it was 75% for those using Covishield – the domestically produced version of the Oxford-astrazeneca vaccine.
As on Wednesday, 16.3 million doses of the two vaccines have been administered to people across the country.
Covaxin uses an inactivated virus paired with an adjuvant – a chemical that boosts immune response. According to the Indian Council of Medical Research (ICMR), which jointly developed the vaccine, the result puts the vaccine at par with other global front-runners.
“Covaxin has been literally developed from scratch in India; the only thing that is foreign about the vaccine is the virus strain that came from China through a medical student, and that was isolated at Icmr-national Institute of Virology (NIV) in Pune on March 9. The virus isolate was transferred to Bharat Biotech around the end of April,” said Dr Balram Bhargava, director general, ICMR.
“Animal challenge studies were done in NIV. The process started during the peak of lockdown, and everything was successfully managed under that restricted environment, till we reached phase 2/3 trials stages. It is a great achievement. Also, the support that the Government of India provided at every step because it had faith and trust in the Indian scientists, helped in streamlining the entire process,” said Bhargava.
Experts in the field also appreciated the results. “This is a scheduled interim analysis and shows that the vaccine is working well. This is based on 43 cases but trial will be completed with final figures when they get to 130 cases. It is unlikely that results will be very different at the end but range will be narrower,” said Dr Gagandeep Kang, one of the country’s top vaccine specialists.
Dr Randeep Guleria, director, All India Institute of Medical Sciences, said, “For a respiratory vaccine, efficacy of 81% is very good.”
While Covaxin is based on a tried-and-tested platform, the other vaccine India is giving to its people – Covishield – makes use of a newer Trojan horse-like technique known as the adenovirus platform. This vaccine, developed by University of Oxford and British drugmaker Astrazeneca, showed an efficacy rate of 70% during clinical trials.
An efficacy higher than 50% is considered acceptable, according to World Health Organization (WHO) norms.
Two other vaccines that are being used widely around the world use a breakthrough technology known as the MRNA platform, and report an efficacy rate above 95%. But both of these require freezing temperatures to be stored or transported.
Covaxin is stable at 2°C to 8°C, temperatures that can be typically achieved by refrigerators, and is shipped in ready-touse liquid formulation that permits distribution using existing vaccine supply chain channels.
According to the company, the product has a 28-day open vial policy as a unique product characteristic, which helps reduce vaccine wastage by approximately 10-30%. This means, each vial of 10ml, which translates into 20 doses, can continue to be used for up to 28 days after opening.
“BBV152 is based on an established manufacturing platform with a better safety profile when compared to other vaccine platforms. The inclusion of the ALGEL-IMDG adjuvant enhances T-cell immune responses to Covid-19, leading to long-term protection,” Bharat Biotech said in a statement.
The Phase 3 study enrolled 25,800 participants between 18 and 98 years of age, including 2,433 over the age of 60 and 4,500 with comorbidities. The primary endpoint of Phase 3 clinical trial is based on the first occurrence of Pcr-confirmed symptomatic (mild, moderate, or severe) Covid-19 with onset at least 14 days after the second dose is given.
Analysis from NIV also indicated that the vaccine induced antibodies under lab conditions against the UK variant B.1.1.7.
At least 40 countries globally have expressed their interest in Covaxin.
“These countries are highly satisfied with the safe, inactivated vaccine technology and robust data package for safety and immunogenicity,” the company said.
On February 24, Bharat Biotech presented a proposal to the Central Drugs Standards Control Organisation to conduct Phase 3 clinical trials in children in the 5-18 age group. But, the expert committee sought efficacy and safety data from the ongoing Phase 3 clinical trial in adults, along with the age subgroup analysis. The committee also asked the company to revise the trial design to make it phase a 2/3 trial and submit a revised protocol.
Covaxin is given at an interval of 28 days, and the company says protective immunity begins to build two weeks after the second dose. During trials, participants were given the doses at the 28-day interval, but this gap is likely to be allowed to be extended for the general public to account for logistical challenges. The Union government has said the second doses of Covaxin as well as Covishield can be given between 4-6 weeks after the first.