A row between pharmaceutical firms Moderna and Pfizer/BioNTech comes to court in London on Tuesday over patents for Covid vaccine technology that helped save millions of lives during the pandemic.

At issue is US firm Moderna's claim that its American competitor Pfizer and its German partner BioNTech breached patent law over its Comirnaty vaccine.

Moderna claims it is due compensation for products manufactured after March 7 last year. But Pfizer and BioNTech deny infringement, and want two Moderna patents withdrawn as "invalid".

The hearing is due to start at the High Court in London from 0930 GMT and is expected to last until mid-May. A ruling will come at a later date.

Moderna has filed similar patent infringement claims against Pfizer and BioNTech elsewhere, notably in the United States and Germany.

The companies earned billions of dollars from the use of cutting-edge Messenger RNA (mRNA) technology in Covid jabs.

Such vaccines work by delivering genetic instructions to turn some of the host's cells into virus-like particles, priming the immune system to mount a response.

Such vaccines were approved within months of a global pandemic being declared by the World Health Organization in March 2020.

Moderna said in 2020 that it would not enforce Covid-19-related patents while the pandemic continued.

But it announced in March last year that it expected its intellectual property to be respected in non low- and middle-income countries where supply was no longer an issue.

A Moderna spokesman on Monday said that the company will on Tuesday argue that Pfizer and BioNTech infringed two of its mRNA patents.

"Moderna is confident in the breadth, depth, and strength of its platform, which is protected by multiple patents," he told AFP.

Pfizer/BioNTech, however, are expected to argue that Moderna pledged not to sue over its Covid vaccine technology patents.