Moderna has developed a new version of its COVID-19 vaccine which has shown promise against the Omicron variant much more than existing shots.

According to the US drug major, the new vaccine targets several mutations abd produced a stronger immune response against the major virus variants, including Omicron and Delta, than the company's current shots, CNBC reported.

The biotech company's redesigned vaccine targets nine mutations found in the Beta COVID variant, as well as the original strain of the virus that first emerged in China's Wuhan in late 2019. Four of the mutations targeted by the updated vaccine are shared with Omicron.

A 50-microgram dose of Moderna's new vaccine doubled the antibodies, which block the virus from infecting human cells, against the Omicron variant six months after injection compared with the original booster at the same dosage, the data indicated.

The updated shot also increased antibody levels against the Delta variant six months after injection, though they were lower than the response observed with Omicron and did not show superior results in comparison to the original booster, according to the findings posted online, and not peer-reviewed yet.

The most common side effects of the updated 50-microgram shot were injection site and muscle pain, fatigue and headache, according to the data. In a statement, Moderna CEO said that the data on the shot with the Beta variant demonstrates that updating the vaccines to target mutations is the right strategy to fight COVID moving forward, the report said.

Moderna and Pfizer, in the wake of the Omicron wave, earlier this year announced that they are developing new shots that target multiple virus variants in the hope of producing vaccines that provide longer-lasting protection against infection.

The current vaccines were developed to recognise the spike protein, which the virus uses to invade human cells, of the Wuhan strain of COVID. But the more the spike protein has evolved, the less likely the antibodies produced by the vaccine are able to recognise the virus and fight it, which reduces the efficacy of the shots.

Two doses of the original vaccines still provide strong protection against hospitalisation, though effectiveness against severe illness also has dropped. Third shots of the current vaccine also boost protection against infection and hospitalisation.

Moderna is also developing an additional vaccine that includes the Wuhan strain and 32 mutations present in the omicron COVID variant. The company expects initial data on that shot in the second quarter of this year, the report said.