Covaxin effective against Delta variant of coronavirus, says U.S.' health research institute

Covaxin, June 30: Bharat Biotech’s Covaxin which has been developed in collaboration with the Indian Council of Medical Research (ICMR) has effectively neutralized both Alpha and Delta variant of coronavirus, revealed the studies recently conducted by the US National Institute of Health (NIH).

Two studies were carried out wherein blood serum from people who had received Covaxin was collected and examined. The results suggest that the vaccine generates antibodies that effectively neutralize the B.1.1.7 (Alpha) and B.1.617 (Delta) variants of SARS-CoV-2, first identified in the UK and India, respectively, said NIH, the top American health research institute, in its press release. SARS-CoV-2 is a virus that causes Covid-19 disease.

The results from two studies of blood serum from people who had received Covaxin suggest that the vaccine generates antibodies that effectively neutralize the B.1.1.7 (Alpha) and B.1.617 (Delta) variants of SARS-CoV-2, first identified in the UK and India, respectively,” the NIH said.

Covaxin comprises a disabled form of SARS-CoV-2 that cannot replicate but still stimulates the immune system to make antibodies against the virus.

Covaxin is safe and well-tolerated, according to the published results from a phase 2 trial of the vaccine. The NIH further said the safety data from a phase 3 trial of Covaxin will become available later this year.

Meanwhile, unpublished interim results from the phase 3 trial indicate that the vaccine has 78 per cent efficacy against symptomatic disease, 100 per cent efficacy against severe Covid-19, including hospitalization, and 70 per cent efficacy against asymptomatic infection with SARS-CoV-2, the virus that causes Covid-19,” he studies revealed.

The NIH, which has a history of strong scientific collaboration with India said that an adjuvant developed with funding from it has contributed to the success of the highly efficacious Covaxin.

Also Read: DCGI approves Covaxin clinical trials for children aged 2-18 years


Adjuvants are substances formulated as part of a vaccine to boost immune responses and enhance a vaccine’s effectiveness.

I am pleased that a novel vaccine adjuvant developed in the US with NIAID support is part of an efficacious Covid-19 vaccine available to people in India,” Anthony S Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), part of NIH, was quoted as saying.

The adjuvant used in Covaxin, Alhydroxiquim-II, was discovered and tested in a laboratory by the biotech company ViroVax LLC of Lawrence, Kansas with support from the NIAID Adjuvant Development Program.

Alhydroxiquim-II is the first adjuvant in an authorized vaccine against infectious disease to activate receptors TLR7 and TLR8 plays a vital role in the immune response to viruses.

Moreover, the alum in Alhydroxiquim-II stimulates the immune system to search for an invading pathogen. Molecules that activate TLR receptors stimulate the immune system powerfully, but the side effects of Alhydroxiquim-II are mild, the NIH said.

There are four variants of concern of the coronavirus disease — Alpha, Beta, Gamma, and Delta — with Delta Plus being a sub-lineage of the Delta variant which is also a variant of concern.

Recently, even the Centre said that the two vaccines — Covaxin and Covishield — are effective against the Delta variant of coronavirus.

ICMR Director General Balram Bhargava, in a press conference last week said Covishield and Covaxin work against SARS-CoV-2 variants Alpha, Beta, Gamma, and Delta, while effectiveness tests against the Delta Plus variant are ongoing.

Also Read: Confused between Covishield and Covaxin? Read what this new study says


Besides, several other studies suggest Covaxin may be effective against multiple variants of the coronavirus.

The results of Phase 3 clinical trials of Bharat Biotech’s Covaxin showed the vaccine against Covid-19 is 77.8 per cent effective.

Bharat Biotech had said last month that it expects approval for its Covaxin from the World Health Organisation for emergency use listing during July-September. Covaxin has been administered to roughly 25 million people to date in India and elsewhere.