French and British pharmaceutical giants Sanofi and GlaxoSmithKline’s Covid-19 vaccine candidate showed a strong immune response in adults ages 18 to 95 and no safety concerns in its Phase 2 trial, the companies said in a news release Monday. A large Phase 3 trial of the vaccine is expected to begin in the coming weeks, they said.
The trial enrolled 722 volunteers in the United States and Honduras who received two injections 21 days apart and at three different dose levels. The companies said the vaccine triggered neutralizing antibodies comparable to those generated by natural infection, with higher levels among people ages 18 to 59. Participants who had previously been infected with Covid-19 showed high levels of neutralizing antibodies after a single dose, suggesting the shot may work as a booster, the companies said.
The Phase 2 results have not yet been peer-reviewed or published in a medical journal.
What's next: The companies said they will soon start a global Phase 3 trial, which is expected to enroll more than 35,000 adults from a range of countries. The trial will use the 10 microgram dose of the protein-based vaccine in combination with GSK’s immune-boosting adjuvant. The companies will also conduct studies with various variant formulations to assess the vaccine as a booster, regardless of the initial vaccine a person received.
With positive Phase 3 results and regulatory reviews, the vaccine could be approved for use in the fourth quarter of 2021, the companies said.
“Our Phase 2 data confirm the potential of this vaccine to play a role in addressing this ongoing global public health crisis, 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,” Thomas Triomphe, executive vice president and global head of Sanofi Pasteur, said in the release.
“With these favorable results, we are set to progress to a global Phase 3 efficacy study. We look forward to generating additional data and working with our partners around the world to make our vaccine available as quickly as possible.”
Late last year, Sanofi and GlaxoSmithKline delayed release of their vaccine after interim results showed insufficient immune responses in the elderly.