Sanofi-GSK Covid-19 vaccine gets nod to start phase-3 trials in India

India part of 35,000 volunteer global efficacy trial

French pharmaceutical giant Sanofi and its British partner GlaxoSmithKline (GSK) plc have received approval from the Drugs Controller General of India (DCGI) to conduct a part of the global Phase 3 efficacy trial of their jointly developed Covid vaccine in India.

 The approval by DCGI marks the first such global trial for a foreign Covid vaccine to be conducted in India — the enrolments are expected to begin soon.

India will be part of the global randomised, double-blind Phase 3 study to assess the safety, efficacy, and immunogenicity of their vaccine. This will include more than 35,000 adult volunteers across the US, Asia, Africa, and Latin America.

With a trial arm in India, this will make the approval process of this vaccine easier here. “India is participating in Sanofi Pasteur’s pivotal Phase 3 study, and subject to subsequent approvals, we should soon begin enrolment of study participants,” said Annapurna Das, country head, Sanofi Pasteur India.

“As the virus continues to evolve, we are anticipating what will be needed in the months and years to come, and accordingly, have adapted our vaccine development programme. We believe our Covid adjuvanted recombinant vaccine can make a significant contribution to the fight against Covid and are committed to initiating clinical programme in India, at the earliest,” she said.

In a two-stage approach, the study will initially investigate the efficacy of a vaccine formulation targeting the original virus strain (D.614), while a second stage will evaluate a second formulation targeting the Beta variant (B.1.351).

“Recent scientific evidence shows that antibodies created against the Beta variant may provide broad cross-protection against other more transmissible variants,” said Sanofi in a statement.  The global Phase 2 interim results showed that the adjuvanted recombinant Covid vaccine candidate achieved high rates of neutralising antibody responses, with 95-100 per cent seroconversion rates.

“After a single injection, high neutralising antibody levels were also generated in participants with evidence of prior SARS-CoV-2 infection, suggesting strong potential for development as a booster vaccine,” said Sanofi.

The unsung hero of vaccines is a component called the adjuvant. It puts a ‘red flag’ on the antigenic component of the vaccine — an inactivated whole or part of a virus or bacteria — and instructs the immune system to mount a defence against that antigen whenever it is encountered. 

Adjuvants are pharmacological or immunological agents that improve the immune response of a vaccine. They may be added to a vaccine to produce more antibodies and longer lasting immunity, thus minimising the dose of the antigen needed. 

An antigen is any substance that causes the immune system to produce antibodies against it. It can be any substance like chemicals, viruses, bacteria that the immune system does not recognise and tries to fend off. 

In the partnership between the two companies, Sanofi provides its recombinant antigen and GSK contributes its pandemic adjuvant — both established vaccine platforms that have proven successful against influenza.

A recombinant vaccine is one that is developed by inserting the deoxyribonucleic acid (DNA) encoding an antigen that stimulates an immune response into the bacterian or mammalian cells. It is made using recombinant DNA technology. The recombinant technology, combined with GSK’s adjuvant, is designed to offer temperature stability, making it easier to distribute globally when the vaccine can be stored at normal refrigerator temperature.

“It is also designed to offer the potential to generate high and sustained immune responses, and the potential to prevent virus transmission,” said Sanofi. Apart from the GSK adjuvanted Covid vaccine, Sanofi is developing a messenger ribonucleic acid (or mRNA) vaccine in collaboration with Translate Bio — an mRNA therapeutics company developing potentially transformative medicines to treat diseases caused by protein or gene dysfunction.