Explained: As Govt Clears Bharat Biotech’s Nasal Covid-19 Vaccine, Know How It Works

Bharat Biotech’s intranasal Covid-19 vaccine was approved for restricted emergency use in adults, on Tuesday, September 6, 2022. 

The Central Drugs Standard Control Organisation (CDSCO) has granted restricted emergency use authorisation to the vaccine, for inoculation in people aged 18 years and above, the Union Minister of Health and Family Welfare, Mansukh Mandaviya, announced on Twitter Tuesday.

The intranasal recombinant Covid-19 vaccine, called BBV154, is India’s first nasal vaccine for protection against Covid-19. A recombinant vaccine contains the modified parts of pathogenic organisms such as bacteria or viruses, which stimulate an immune response in the host cells. 

The scientific name for BBV154 is ChAd36-SARS-CoV-2-S. ‘ChAd’ means that BBV154 is a Chimpanzee Adenovirus-Vectored vaccine.

On August 15, 2022, Bharat Biotech announced that the pharmaceutical company has completed clinical development for the Phase III trials and booster doses for BBV154, the intranasal vaccine for Covid-19 manufactured by the company. Bharat Biotech said that BBV154 is proven to be safe, well-tolerated and immunogenic in the subjects in controlled clinical trials. 

The fact that the vaccine is immunogenic means that it produced an immune response in the subjects involved in the Phase III trials.

What Is BBV154?

BBV154 is a novel adenovirus-vectored intranasal vaccine for Covid-19. Adenovirus-vectored vaccines are the vaccines in which adenoviruses are used as vectors for delivering a particular antigen into the body of a host, where the cells will read the foreign particle, and create antibodies against it. 

An intranasal vaccine stimulates a broad immune response by producing a wide range of antibodies including neutralising Immunoglobulin G (IgG) and mucosal Immunoglobulin A (IgA). The vaccine also initiates T cell responses. 

According to the official website of Bharat Biotech, immune responses in the nasal mucosa, which is the site of infection, are essential to block the infection and stop the transmission of Covid-19. 

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What Are The Advantages Of BBV154?

Intranasal SARS-CoV-2 vaccines are likely to prevent infection and transmission, and also prevent disease. 

According to Bharat Biotech, the advantages of BBV154 are that it is non-invasive and needle-free, can be administered easily, is ideally suited for children and adults, and has scalable manufacturing. 

The use of this vaccine will eliminate needle-associated risks such as injuries and infections. Also, the nasal mucosa has an organised immune system because of which the nasal route serves as one of the best regions for vaccination.

Where Does BBV154 Produce Antibodies?

Since BBV154 is an intranasal vaccine, it has the potential to produce local antibodies in the upper respiratory tract, according to the statement. This can potentially reduce infection and transmission of SARS-CoV-2, the causative organism of Covid-19. 

The optimal temperature range for the storage and distribution of BBV154 is two to eight degrees Celsius.

Bharat Biotech said in a statement that two separate and simultaneous clinical trials were conducted to evaluate BBV154 as a two-dose schedule, and a heterologous booster dose for subjects who have previously received two doses of the two commonly administered Covid-19 vaccines in India — Covishield and Covaxin. 

The Hyderabad-based firm also said data from the clinical trials have been submitted for approval to the National Regulatory Authorities (NRAs), the gatekeepers of the supply chain of medical products. 

The Phase III trials for the two-dose schedule, also known as primary dose schedule, were conducted for safety and immunogenicity of BBV154 in 3,100 subjects, and compared with Covaxin, India’s first indigenous Covid-19 vaccine. The trials were conducted in 14 trial sites across the country. 

In the heterologous booster dose study, a third dose of BBV154 vaccine was administered to 875 subjects who were fully vaccinated with licensed Covid-19 vaccines. The study was conducted to evaluate the safety and immunogenicity of BBV154 as a booster dose. The trials were conducted in nine sites across the country.

BBV154 had shown successful results in the Phase I and Phase II clinical trials. The vaccine candidate has been formulated to allow intranasal delivery. An important objective behind the development of BBV154 is to ensure that it is cost-effective in low- and middle-income countries.

BBV154 has been developed in partnership with Washington University St Louis, Missouri. 

In the statement, Suchitra K Ella, Joint Managing Director, Bharat Biotech, said that vectored vaccines enable faster development of target vaccines in response to emerging variants of concern. She stated that BBV154 has the double benefit of enabling faster development of variant -specific vaccines and easy nasal delivery. “It promises to become an important tool in mass vaccinations during pandemics and endemics,” she said. 

The Working Of BBV154

The BBV154 vaccine is developed by modifying a Chimpanzee adenovirus into a viral vector that will carry the stabilised spike protein of SARS-CoV-2 to the host cells. When the BBV154 vaccine is administered into a person, the immune cells in the body will express the stabilised spike protein. As a result, the body will produce antibodies against the spike protein of SARS-CoV-2. 

If a person is naturally exposed to SARS-CoV-2, the immune system will prevent Covid-19 infection in both upper and lower respiratory tracts due to the presence of antibodies. Thus, BBV154 has the potential to block SARS-CoV-2 and prevent the transmission of Covid-19.