Drugmakers Sanofi and GlaxoSmithKline said on Wednesday they will seek regulatory approval for a new Covid-19 vaccine after human trials showed it provided a high level of protection against the disease.

Late-stage trials found that two doses of the vaccine were about 58 per cent effective in preventing infection and 75 per cent effective in preventing moderate to severe disease, the companies said in a statement. A separate study on the vaccine’s use as a booster showed that it “induced a significant increase in neutralising antibodies,’‘ they said.

“The evolving epidemiology of Covid-19 demonstrates the need for a variety of vaccines,'' Roger Connor, president of GSK Vaccines, said in a statement.

The Sanofi-GSK vaccine uses “a well-established approach that has been applied widely to prevent infection with other viruses including pandemic flu,'' he said. “We are confident that this vaccine can play an important role as we continue to address this Covid pandemic and prepare for the post-pandemic period.”

The drugmakers said they plan to seek regulatory approval from both the US Food and Drug Administration and the European Medicines Agency, which regulates drugs in the European Union.

Sanofi and GlaxoSmithKline had planned for their vaccine to be ready last year but early trials showed the vaccine produced an “insufficient” immune response in people over 60 because it didn't contain enough of the material that triggers the production of disease-fighting antibodies.

Late-stage trials of the current formulation of the Covid vaccine were conducted on 10,000 adults in the US, Asia, Africa and Latin America. The companies didn't provide a breakdown of the vaccine's effectiveness for different age groups. Full results from the study will be published later this year.

Authorisation of the shot would bolster efforts to combat a pandemic that has already taken more than 5.9 million lives worldwide as the makers of existing vaccines struggle to produce enough doses to meet demand. GSK and Sanofi have signed agreements to supply millions of doses to the US, EU, Canada and developing countries.