Sanofi and GlaxoSmithKline plan to seek authorization for their experimental coronavirus vaccine in the U.S. and abroad after their shot prevented COVID-19 in a large clinical trial.
Summary study results released by press release Wednesday showed a two-dose regimen provided complete protection against severe disease and hospitalization in the study. The vaccine was 75% effective against moderate COVID-19, and about 58% against all symptomatic disease. No new safety concerns were reported, the companies said.
Two of the world's biggest vaccine makers, Sanofi and GSK have been working together since 2020 and received a large supply contract from the U.S. government's Operation Warp Speed initiative. But development of their COVID-19 shot hit a series of setbacks and delays, including disappointing results in early testing that forced the companies to redesign the vaccine.
With Wednesday's results, the shot, which is based on established vaccine-making technology, could have a chance at being used as a booster for people who previously received other vaccines. In the U.S. and Europe, however, Sanofi and GSK will face a crowded market dominated by Pfizer, Moderna and, to a lesser extent, AstraZeneca and Johnson & Johnson.
The companies' vaccine might become more important in other countries, however. Based on an older protein-based technology, the shot can be stored in refrigerators, while mRNA vaccines from Pfizer and Moderna require colder freezers.
Vaccine supplies still aren't available in large quantities in some parts of the world. Many countries in Africa have immunization rates below 20%, while some in the Middle East, Central Asia and South Asia remain below 50%.
The protection offered by Sanofi and GSK's vaccine, while high against severe disease and hospitalization, appears more modest than original numbers reported by Pfizer and Moderna. But the companies began recruiting volunteers into their trial in May 2021 and, as a result, some were exposed to more infectious variants like delta and omicron, potentially affecting the vaccine's effectiveness.
"No other global Phase 3 efficacy study has been undertaken during this period with so many variants of concern, including omicron, and these efficacy data are similar to the recent clinical data from authorized vaccines," Thomas Triomphe, Sanofi's executive vice president for vaccines, said in a statement.
The company hasn't completed genetic sequencing of all its positive cases, but preliminary data showed that the shot was 77% effective in people infected with the delta variant, which was first detected in late 2020. The companies didn't provide any information on omicron, which was first detected in November 2021.
Additional data disclosed by Sanofi and GSK showed the vaccine can boost immune response in people initially vaccinated with Pfizer's, Moderna's and J&J's products, providing support for its use as a third or late shot. Neutralizing antibody levels rose between 18 to 30 times in people receiving the shot as a booster, the companies said.
The companies are expected to sell the vaccine, if approved, at a price low enough to cover costs, which are estimated to be about $3 to $5 a dose, according to Peter Welford, an analyst at Jefferies. The July 2020 agreement with the U.S. government promised up to $2.1 billion to aid development and scale up manufacturing in return for at least 100 million doses.
Under the collaboration between the two drugmakers, Sanofi provides the protein-based vaccine and GSK supplies an "adjuvant," or a chemical that helps stimulate the immune system.