Sanofi and GSK plan to ask regulators to authorize their COVID-19 vaccine

Drugmakers Sanofi and GlaxoSmithKline announced Wednesday they are planning to ask regulators to authorize their new COVID-19 vaccine candidate.

The companies said data shows the shot works either as a primary vaccine, with 100% effectiveness against severe disease and hospitalization, or as a booster shot to raise antibody levels.

Although they are submitting a request for authorization more than a year after Pfizer-BioNTech, Moderna and Johnson & Johnson were approved in the U.S., Sanofi and GSK are hoping to differentiate their vaccine because it is based on a more conventional protein-based vaccine technology.

Known as a recombinant protein vaccine, it uses the spike protein -- which COVID uses to enter and infect cells -- to help the body recognize the virus so it can fight it off if a person becomes infected.

This is different from messenger RNA, or mRNA, technology, which is used by Pfizer and Moderna and teaches the body's cells how to make proteins that trigger immune responses.

It's also different from Johnson & Johnson's vaccine, which is a viral vector vaccine and combines COVID genetic material with genes from the common cold-causing adenovirus to trigger an immune response.

"The evolving epidemiology of COVID-19 demonstrates the need for a variety of vaccines," Roger Connor, president of GSK Vaccines, said in a statement. "Our … protein-based vaccine candidate uses a well-established approach that has been applied widely to prevent infection with other viruses including pandemic flu. We are confident that this vaccine can play an important role as we continue to address this pandemic and prepare for the post-pandemic period."

The companies said their data from Phase 3 clinical trials showed two doses of their candidate, called VAT08, was 100% effective against severe disease and hospitalization from COVID-19, according to a company statement.

The vaccine was also 75% effective against moderate-to-severe disease and about 58% effective against symptomatic disease.

Early data also indicated the vaccine was 77% effective against symptoms linked to the delta variant.

When used as a booster shot for an already-approved vaccine, the Sanofi-GSK vaccine increased antibody levels 18- to 30-fold, according to the company.

Additionally, when trial participants were given two doses of the vaccine candidate and then a booster shot, antibody levels rose 84- to 153-fold.

"We're very pleased with these data, which confirm our strong science and the benefits of our COVID-19 vaccine," Thomas Triomphe, executive vice president of Sanofi Vaccines, said in a statement. "The Sanofi-GSK vaccine demonstrates a universal ability to boost all platforms and across all ages."

The study also showed no severe reactions or safety concerns from the vaccine in any age group.

The drugmakers are currently in discussions with the U.S. Food and Drug Administration and European regulators and plan to submit their data soon.2

It comes just one month after another pharmaceutical company, Novavax, asked the FDA to authorize its COVID-19 vaccine candidate, which also uses protein-based technology.

ABC News' Sony Salzman contributed to this report.