Photo used for illustrative purpose.

The lawsuits set up a high-stakes showdown between the leading manufacturers of COVID-19 shots that are a key tool in the fight against the disease.

"Moderna believes that Pfizer and BioNTech's COVID-19 vaccine Comirnaty infringes patents Moderna filed between 2010 and 2016 covering Moderna's foundational mRNA technology," the US-based biotech firm said in a statement.

"Pfizer and BioNTech copied this technology, without Moderna's permission, to make Comirnaty," Moderna said. Pfizer and BioNTech said they have not fully reviewed the complaint, but expressed surprise over the litigation.

"The Pfizer/BioNTech COVID-19 vaccine was based on BioNTech's proprietary mRNA technology," a statement said. "We will vigorously defend against the allegations of the lawsuit."

The mRNA technology used in the Moderna and Pfizer-BioNTech shots differs from that in traditional vaccines, which rely on injecting weakened or dead forms of a virus to allow the immune system to recognize it and build antibodies.

Instead, mRNA vaccines deliver instructions to cells to build a harmless piece of the spike protein found on the surface of the virus that causes COVID-19.

After creating this spike protein, cells can recognise and fight the real virus, hailed as a major advancement in development of vaccines.

Agence France-Presse