The French and British drugmakers Sanofi and GSK are ready to seek approval from regulators for their Covid-19 vaccine after reporting positive results from late-stage clinical trials.

The firms are hoping to catch up with rivals after falling far behind in the race to develop Covid-19 shots. Their product was delayed by an early dosing error during trials, initially disappointing results in older people and other issues. It will be available as a two-dose vaccine and as a booster.

The companies will now file for approval from regulators, including the US Food and Drug Administration and the European Medicines Agency, while a rolling review with the UK regulator, the Medicines and Healthcare products Regulatory Agency, is already under way.

Sanofi developed the jab, while GSK, the world’s biggest vaccine maker by sales, is supplying its adjuvant technology, to boost the body’s immune response.

It relies on a conventional protein-based approach, compared with the newer mRNA technology used by Pfizer/BioNTech and Moderna, which makes it easier to store and transport.

The companies said the phase 3 efficacy trials showed that two doses of the jab provided 100% efficacy against severe Covid-19 disease and hospitalisations; 75% efficacy against moderate or severe Covid-19 disease; and 57.9% efficacy against any symptomatic Covid-19 disease. They said the latter is in line with expected vaccine effectiveness given the emergence of several variants of concern, such as Omicron, and similar to other vaccines.

A separate trial showed that the jab boosted antibody levels against the virus 18 to 30 times across all age groups, when used in people who had been given two doses of other vaccines such as the Pfizer/BioNTech, Modern and Oxford/AstraZeneca shots.

Thomas Triomphe, the executive vice-president of Sanofi Vaccines, said: “The Sanofi-GSK vaccine demonstrates a universal ability to boost all platforms and across all ages.

“We also observed robust efficacy of the vaccine as a primary series in today’s challenging epidemiological environment. 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 authorised vaccines.”

Roger Connor, the president of GSK’s vaccines arm, said: “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.”