LONDON, July 10 (Reuters) - Pfizer ( PFE ) and its German

partner BioNTech asked London's Court of Appeal on Thursday to

overturn a ruling that their COVID-19 vaccine infringed one of

Moderna's ( MRNA ) patents, in the latest round of a long-running legal

dispute between the two sides.

A year ago, the High Court ruled that one of Moderna's ( MRNA )

two patents relating to the messenger RNA (mRNA)

technology that underpinned its COVID-19 vaccine was valid and

that Pfizer ( PFE ) and BioNTech's Comirnaty vaccine

had infringed it, meaning Moderna ( MRNA ) is entitled to damages in

relation to sales after March 2022.

The court also ruled last July that the other Moderna ( MRNA ) patent

under challenge in the case was invalid.

Pfizer ( PFE ) and Moderna ( MRNA ) are seeking to overturn the decision

that one of the patents is valid, after Judge Richard Meade gave

the two companies permission to appeal against his decision.

They argue Moderna's ( MRNA ) developments of mRNA technology were

obvious developments of previous work, rendering the patent

invalid, though Moderna ( MRNA ) says the judge's ruling should be

upheld.

Pfizer ( PFE ) and BioNTech generated more than $3.3 billion in

revenue from global sales of their vaccine Comirnaty last year,

while Moderna ( MRNA ) generated $3.2 billion from its vaccine Spikevax,

according to company reports. Sales of both vaccines declined

significantly between 2023 and 2024 after the pandemic ended.

Pfizer ( PFE ) and BioNTech had sued Moderna ( MRNA ) in London in September

2022, seeking to revoke the two patents held by Moderna ( MRNA ), which

hit back days later alleging its own patents had been infringed.

The London lawsuits are just one part of a global battle

between Pfizer ( PFE ), BioNTech and Moderna ( MRNA ) over their competing

vaccines, which helped save millions of lives during the

pandemic.

The companies have also been involved in proceedings in

Germany - where a court ruled in Moderna's ( MRNA ) favour in March - the

United States Patent Office, which held that two Moderna

COVID-19 vaccine patents were invalid, and elsewhere.