Sanofi, GSK start phase 2 trial of their COVID-19 vaccine, phase 3 could begin by April

Paris [France], February 22 : Sanofi and GlaxoSmithKline (GSK) said on Monday they had begun a phase 2 trial of their COVID-19 vaccine candidates, and if results are positive, a phase 3 study could start in the second quarter of 2021.
According to CNN, the "protein subunit" vaccine uses Sanofi's recombinant antigen technology with a GlaxoSmithKline adjuvant, an immune booster. The phase 2 study will include 720 volunteers aged 18 and older in the United States, Honduras and Panama.
The trial will assess the dosage of the companies' vaccine; three different antigen doses will be tested with a fixed adjuvant dose and the two injections will be given 21 days apart.
CNN further reported that phase 1/2 trials showed the vaccine candidate elicited an immune response in younger adults that's comparable to patients who recovered from COVID-19, but the vaccine did not produce the desired immune response in older adults.
The second phase of the trial will include equal numbers of adults aged from 18 to 59 years, and 60 years and above.
"Over the past few weeks, our teams have worked to refine the antigen formulation of our recombinant-protein vaccine, based on learnings from our initial Phase 1/2 study," Thomas Triomphe, executive vice president and head of Sanofi Pasteur, said in a statement quoted by CNN.
"We are confident that our vaccine candidate has strong potential and we are very encouraged by the latest preclinical data," Triomphe added.
The companies said that the vaccine could be available in the fourth quarter if trial results are positive and the vaccine is authorised.
In statements, the companies also said Sanofi has begun work against new coronavirus variants "which will be used to inform next stages of the Sanofi/GSK development program."