Explained: All You Need To Know About Sanofi-GSK’s COVID Vaccine

French pharma giant Sanofi and UK's GlaxoSmithKline Plc (GSK) reported Monday, 17 May, that the clinical trials of their COVID-19 vaccine showed strong immune response, as the world races to deliver vaccines to help end the pandemic.

The vaccine candidate "achieved strong rates of neutralizing antibody responses, in line with those measured in people who have recovered from COVID-19, in all adult age groups in a Phase 2 study with 722 volunteers," the companies said in a statement.

A global pivotal Phase 3 study is expected to start in the coming weeks.

This comes after a setback in December last year, when the companies said the vaccine candidate failed to induce a strong enough immune response in people 50 years and older in the interim results. The companies had added that the vaccine would only be ready by the end of 2021.

How Does The Vaccine Work?

It is a recombinant protein-based COVID-19 vaccine, which means a vaccine produced using a viral particle with the aid of recombinant technology.

Here, Sanofi provides its recombinant antigen or the anti-viral particle. Meanwhile, GSK contributes its pandemic adjuvant or the agent that stabilizes it. The adjuvant enhances the immune response to the vaccine, thereby increasing the efficacy too.

This technology has been used and proven successful against influenza earlier.

Meanwhile, in addition to the adjuvant recombinant protein-based vaccine in collaboration with GSK, Sanofi is developing a messenger RNA vaccine in partnership with Translate Bio.

What Are the Advantages of the Technology Used?

The technology is designed to offer the advantages of stability at temperatures used for routine vaccines.

This makes it easily implementable and easier to distribute at a global scale through existing infrastructures where vaccines are stored at normal refrigerator temperature, the companies said.

It also offers the potential to generate high and sustained immune responses, and the potential to prevent virus transmission, it statement added.

What Stage Is the Trial In?

The experimental vaccine is in the Phase 2 trial. The companies said the Phase 2 interim results show that the vaccine candidate triggered strong immune response amongst adults of all age groups with 95 percent to 100 percent seroconversion rates or production of antibodies.

The research also showed a high immune response after a single dose in patients who had earlier been infected with Covid, showing the vaccine’s strong potential as a booster shot.

The trails were conducted with 722 volunteers.

Based on these positive Phase 2 interim results, the companies plan to initiate a global Phase 3 study in the coming weeks with more than 35,000 adult participants from a broad range of countries.

It will assess the efficacy of two vaccine formulations including the D614 (Wuhan) and B.1.351 (South African) variants.

How Is It Different From Covishield and Covaxin?

Covishield or the Oxford-AstraZeneca vaccine which is being manufactured by the Serum Institute (SII) is a viral vector vaccine. (links to the FIT story on this)

Meanwhile, Covaxin, the indigenous vaccine by Bharat Biotech in collaboration with the Indian Council of Medical Research (ICMR) is an inactivated COVID-19 vaccine.

Covishield has an efficacy of 62-90 per cent while the clinical efficacy of Covaxin was found to be 78 per cent in the interim data of the phase 3 clinical trial. Full data of phase 3 has still not been released by Bharat Biotech.