The UK High Court has ruled that two GSK respiratory syncytial virus (RSV) vaccine patents are invalid in an action involving Pfizer, as both companies battle to become the first to launch an RSV vaccine on the UK market.

Mr Justice Mellor ruled on 7 October that both patents in suit, EP258 and EP710, which cover recombinant RSV antigens, were invalid for obviousness over each piece of prior art.

Both parties at the time of trial in June 2023 were on the “brink” of launching their respective vaccines – GSK’s Arexvy, aimed at the elderly and Pfizer’s Abrysvo, aimed at both elderly and the maternal population.

The judge has now ruled “I had clear primary evidence of obviousness” from Pfizer’s “impressive” expert witness on vaccinology, Dr Teresa Johnson, and Professor Winfried Weissenhorn, who specialises in structural biology.

Against the prima facie clear case of obviousness on the primary evidence, Mellor did not find the secondary evidence provided by UK-headquartered GSK either “complete enough or anywhere near persuasive enough” to displace that prima facie case.

At the time of trial, there was no vaccine for RSV in the UK, which causes symptoms akin to the common cold but in the very young and old can develop into more serious conditions like pneumonia. It has been a significant target for vaccine development for some years.

Pfizer said the patents were invalid as it attempts to “clear the way” ahead of a commercial launch in the UK of its own RSV vaccine.

It had sought an ‘arrow declaration’ that at the priority date/filing date it was obvious to make an RSV antigen which resembles the antigens covered by the patents in suit.

Pfizer argued that the declaration would serve a “useful purpose” because there was a clear public health interest in having Pfizer’s vaccine made available in the UK.

The judge agreed and granted the declaration.

GSK had also alleged that Pfizer’s product infringed its two patents, but the judge ruled that even if valid, the patents would not have been infringed by the Pfizer product.

In a statement Pfizer said it was “pleased with the decision of the UK High Court finding certain GSK patents concerning RSV-related technology both invalid and not infringed”.

It added it was “confident” in its intellectual property position and would “strongly defend its right to bring its RSV vaccine Abrysvo to patients”.

In June 2024, the UK government announced that it had selected US-headquartered Pfizer to supply five million doses of Abrysvo over the next two years ahead of the GSK vaccine.

GSK is also suing Pfizer in a US district court in Delaware for infringing its RSV vaccine patents through the sale of Abrysvo.

In the UK High Court case, GSK was represented by 8 New Square’s Tom Moody-Stuart KC and 3 New Square’s Katherine Moggridge instructed by Marks & Clerk.

Pfizer was represented by 8 New Square’s Justin Turner KC and 3 New Square’s Thomas Lunt instructed by Gowling WLG.