European drugmakers Sanofi and GSK have announced positive results from late-stage clinical testing of a new vaccine that will be named Vidprevtyn, a media report says.

According to CNN, the companies plan to seek authorisation for the shots in the US and Europe. Vidprevtyn is a protein subunit vaccine, which means it uses harmless protein fragments that teach the immune system how to spot and fight off the SARS-CoV-2 virus, the report said. It is a more traditional type of vaccine than mRNA or adenovirus vector vaccines, which carry the genetic instructions for making the spike protein into cells, where they can then be built and displayed like mug shots for the immune system find and defend against, it added.

These kinds of vaccines can be stored at refrigerator temperatures, making them easier to use in areas that don't have access to ultracold storage. Because they rely on more familiar technology, there's hope that people who've declined other kinds of COVID-19 vaccines may find these kinds of vaccines more palatable.

The vaccine is given in two doses delivered about three weeks apart. The phase 3 trials to test the vaccine enrolled more than 10,000 adults in the US, Asia, Africa and Latin America. A separate study is assessing a third dose of the vaccine as a booster.

After two doses given to people with no antibodies against the SARS-CoV-2 virus, the vaccine was 58 per cent effective at preventing COVID-19 symptoms, 75 per cent effective at preventing moderate or severe COVID-19 and 100 per cent effective against severe COVID-19 disease, including hospitalisations. The new vaccine posted lower numbers against symptomatic illness than the mRNA vaccines made by Pfizer and Moderna, but it was also tested under different conditions when the new variants were circulating.

The companies said the vaccine performed well on its own and as a mix-and-match booster, bumping neutralising antibodies by 18- to 30-fold when given to people who'd gotten Pfizer, Moderna or adenovirus-vector vaccines like the Johnson & Johnson and AstraZeneca shots.