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Bharat Biotech slams recent Covaxin-Covishield antibody study, says report has 'lots of flaws'

(Photo: Reuters)Premium
(Photo: Reuters)

  • Bharat Biotech says in a statement that the study is 'not a peer-reviewed publication, nor statistically & scientifically designed study, the study design and conduct reflect an ad hoc analysis, rather than predetermined hypothesis'
  • Once data from final analysis of phase III studies are available, it will apply for full licensure for Covixain, it adds

Hyderabad-based vaccine manufacturing company Bharat Biotech on Wednesday slammed a recent comparative study of antibodies produced by its vaccine Covaxin and Serum Institute of India's locally produced Covishield vaccine, saying that the study has "lots of flaws."

"A recent comparative report on evaluation of immunogenicity responses to spike protein after 1st and 2nd dose of Indian manufactured vaccines study had lots of flaws. The journal that stated comparative report said more antibodies produced by Covishield than Covaxin," Bharat Biotech said in a statement.

The vaccine making company also clarified that the pan-India study, which accumulated the reactions of healthcare workers who had received both doses of the preventives, was "not a peer-reviewed publication, nor statistically & scientifically designed study."

"It's not a peer-reviewed publication, nor statistically & scientifically designed study, the study design and conduct reflect an ad hoc analysis, rather than predetermined hypothesis. Further, the study was not registered on CTRI website, nor approved by CDSCO & SEC," the company stated.

It is critical to understand the Phase-3 data will first be submitted to CDSCO, followed by peer-reviewed journals, with a timeline of ~ 3 months for publication, and as communicated earlier COVAXIN phase 3 results full trial data will be made public during July, Bharat Biotech said,

The company further stated, "Once data from final analysis of phase III studies are available, Bharat Biotech will apply for full licensure for COVAXIN."

On Monday, Raches Ella, head of business development and advocacy at Bharat Biotech, questioned in tweets why "non-peer-reviewed work" was put out.

In a series of tweets, Ella responded to a media report, "Surprised that media/researchers are concluding based on non-peer-reviewed work. Limitation 1: Spike-based IgG's are not appropriate when evaluating Covaxin, which induces broad antibody responses to Spike, N, and M. Recommend live virus neutralization."

Recently, a pan-India study had claimed that Covishield vaccine produces more antibodies than Covaxin though both generate a “good immune response."

The yet-to-be-published study, posted on the preprint repository MedRxiv on June 4, covered 515 healthcare workers (HCW) — 305 men and 210 women — from 22 cities in 13 states.

Covishield, from the Oxford-AstraZeneca stable, is manufactured by the Serum Institute of India in Pune. Covaxin is the indigenously manufactured vaccine by Hyderabad-based Bharat Biotech in collaboration with ICMR and National Institute of Virology (NIV).

The blood samples of those participating in the study were tested for the quantity of antibodies produced and levels of specific antibodies that are directed to the spike protein of the virus, which is regarded as a proxy for protection, according to a report by news agency PTI.

“Both vaccines elicited good immune response after two doses, although seropositivity rates and antibody levels were significantly higher in Covishield compared to Covaxin," Awadhesh Kumar Singh, lead author of the study and consultant endocrinologist, GD Hospital and Diabetes Institute, Kolkata, said in a tweet.

Seropositivity was observed in a higher number of people vaccinated with Covishield as compared to those immunised with Covaxin.

“Among the 515 HCW, 95% showed seropositivity after two doses of both vaccines. Of the 425 Covishield and 90 Covaxin recipients, 98.1% and 80% respectively, showed seropositivity," said the study authors.

Seropositivity refers to the production of antibodies in an individual.

The study was conducted by researchers from various institutes, including Ahmedabad's Vijayratna Diabetes Centre, Kolkata's GD Hospital and Diabetes Institute, Dhanbad's Diabetes and Heart Research Centre and the Rajasthan Hospital and Mahatma Gandhi Medical College and Hospital in Jaipur.

The rise in anti-spike antibodies was also “significantly higher in Covishield vs Covaxin recipient" at 127 absorbance units per milliliter (AU/mL) and 53 AU/mL respectively, the authors noted.

AU is the unit of measuring antibody levels.

Apart from finding higher seropositivity among Covishield recipients, the study found that seropositivity rate was “significantly more" in participants with an age of 60 or less compared to those above 60.

While factors such as gender, body mass index (BMI) and other comorbidities didn’t make any difference, the seropositivity rate or antibodies in people with type 2 diabetes was found to be significantly lower.

The researchers also compared the post-vaccination immune responses of all participants with those who had a history of COVID- 19, and those who didn’t.

It found that participants who had recovered from COVID-19 at least six weeks before the first dose of both vaccines, and later took both shots, were 100% seropositive, and had higher antibody levels compared to others.

“The past history of SARS-CoV-2 infection elicited a significantly greater median antibody titre, compared to SARS-CoV-2 naïve cohorts, irrespective of the type of vaccine received," the researchers noted.

Breakthrough infections, defined as SARS-CoV-2 infection over two weeks after the second dose, were reported in 4.9% of cases following both vaccines, according to the study authors.

Such infections were noted in 5.5% of people in Covishield, and 2.2% of Covaxin recipients, they said.

Covaxin is an inactivated vaccine that contains the dead virus. Preliminary data of the Phase 3 trials shows that Covaxin has an efficacy rate of 81%. The duration between the two doses is 28 days.

Covishield is based on the viral vector platform and is made from a weakened version of a common cold virus from chimpanzees. The two doses of Covishield are administered 12 weeks apart. It has an efficacy of over 70%.

With inputs from PTI

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