© Joel Saget, AFP/File
French pharmaceuticals giant Sanofi and Britain's GSK reported Monday positive results in clinical trials of their Covid-19 jab following an earlier setback, raising hope it could be added to the world's vaccine arsenal.
The companies said the outcome of the Phase 2 study will enable them to move to a late-stage trial in the coming weeks -- a reversal of fortune after disappointing results in previous research last year.
The experimental vaccine "achieved strong rates of neutralizing antibody responses, in line with those measured in people who have recovered from COVID-19," Sanofi and GSK said in a statement.
The trials were conducted among 722 adult volunteers.
An earlier study in late 2020 showed the vaccine provided a low immune response in older adults. The companies said at the time the vaccine would not be ready until the end of 2021.
The initial failure was a setback that dented French pride as France is the only permanent member of the UN Security Council not to have its own vaccine after successes for Britain, China, Russia and the United States.
"Our Phase 2 data confirm the potential of this vaccine to play a role in addressing this ongoing global public health crisis," said Thomas Triomphe, executive vice president and global head of Sanofi Pasteur.
"As we know multiple vaccines will be needed, especially as variants continue to emerge and the need for effective and booster vaccines, which can be stored at normal temperatures, increases," he said.
The final, Phase 3 trial will be conducted among 35,000 adults "in a broad range of countries", the companies said. It is expected to begin in late May or early June.
It will test the vaccine's efficacy against the strain first found in Wuhan, China in late 2019 and the variant detected in South Africa. The previous candidate was only tested against the variant found in Wuhan.
The companies expect to secure approval from regulators in the last three months of 2021 -- a year after vaccines by Pfizer-BioNTech and Moderna.
Approval late 2021
The firms are combining a Sanofi-developed antigen, which stimulates the production of germ-killing antibodies, with GSK's adjuvant technology, a substance that bolsters the immune response triggered by a vaccine.
The Phase 2 trial show that after a second dose, the vaccine produced a "strong immune response" among adults of all age groups, with rates of seroconversion -- or production of antibodies -- ranging between 95 and 100 percent, Sanofi and GSK said.
The volunteers were between 18 and 95 years old.
The research also showed that one dose produced high levels of antibodies in people who had previously been infected with the coronavirus, which would make the vaccine useful as a booster shot.
Jabs by British pharmaceutical firm AstraZeneca and US company Johnson & Johnson have also been rolled out in Europe.
Sanofi is in talks to supply doses to the United States, Canada and European Union, France Sanofi president Olivier Bogillot told Europe 1 radio.
"Most countries were waiting for the Phase 2 results to be able to initiate orders," Bogillot said.
Sanofi is developing a second vaccine with US firm Translate Bio, using the same messenger RNA technology as Pfizer-BioNTech and Moderna.