A new Covid vaccine shows 100 percent efficacy against severe disease and hospitalizations, its makers say.

Covid Live Updates: Sanofi-GSK Vaccine Results Show It’s Highly Protective Against Severe Disease, Its Makers Say The vaccine, made by the Europe-based pharmaceutical companies Sanofi and GSK, is one of four candidates that received billions of dollars for development from Operation Warp Speed, the Trump administration’s program to accelerate vaccines. The New York Times

Two doses of a new Covid vaccine that is based on a conventional approach achieved 100 percent efficacy against severe disease and hospitalizations, and it could be an effective booster after other Covid shots, the vaccine’s manufacturers announced on Wednesday.

The vaccine, made by the Europe-based pharmaceutical companies Sanofi and GSK, is one of four candidates that received billions of dollars for development from Operation Warp Speed, the Trump administration’s program to accelerate vaccines.

The new vaccine had an efficacy of 75 percent against moderate-to-severe disease. It showed 58 percent efficacy against symptomatic disease in its Phase 3 clinical trial. Although that number is lower than was observed for the mRNA vaccines made by Pfizer-BioNTech and Moderna in their initial trials, it is “in line with expected vaccine effectiveness in today’s environment dominated by variants of concern,” Sanofi and GSK said in a statement. The number of infections observed in the trial was small, however, and the efficacy may have been lower in a bigger trial.

Used as a booster dose after one of the other available coronavirus vaccines, the Sanofi-GSK shot increased antibody levels by 18- to 30-fold. The companies intend to submit the vaccine for authorization to regulatory authorities in the United States and Europe, they said on Wednesday.

Sanofi and GSK were expected to seek authorization for their vaccine last year, but shelved those plans after clinical trials showed disappointing results in older adults. They then developed a stronger version of the vaccine and tested it in new trials.

In laboratory studies, two doses of the Sanofi-GSK vaccine stimulated the production of more neutralizing antibodies than an approved mRNA vaccine, according to the companies. The data have not yet been published. The vaccine was safe and well-tolerated by adults of all ages, the companies said.

The best target for Covid vaccines is a protein called spike that covers the surface of the virus like a crown. While the mRNA vaccines contain the genetic instructions for making the protein, the Sanofi-GSK vaccine uses a slightly modified version of the protein itself to stimulate an immune response.

This is a commonly used approach for vaccines, and so may convince some people who have been hesitant to adopt the newer mRNA technology. Protein-based vaccines are also relatively inexpensive to manufacture and may not require the ultracold storage needed for the mRNA vaccines. Those features make them more likely candidates for rollout in African nations where vaccine coverage is still very low. ...