WHIPPANY, New Jersey: Bayer has opened a new legal front in the long-running battles over COVID-19 vaccine technology, suing several major drugmakers in U.S. courts over alleged misuse of its messenger RNA innovations developed decades before the pandemic.

On January 6, Bayer's Monsanto unit filed patent infringement lawsuits in Delaware federal court against Pfizer, BioNTech, and Moderna, alleging they improperly used its mRNA technology in manufacturing their COVID-19 vaccines, a Bayer spokesperson confirmed.

According to the complaints, the companies copied technology developed by Monsanto scientists in the 1980s to strengthen messenger RNA in crops. Bayer argues that this work reduced mRNA instability and was later used to stabilise the genetic material in vaccines, infringing its patents.

Bayer also filed a separate lawsuit against Johnson & Johnson in the New Jersey federal court on January 6. That complaint alleges that a DNA-based manufacturing process used in Johnson & Johnson's COVID-19 shots infringed Bayer-held patents.

A Moderna spokesperson said the company is aware of the lawsuit and will defend itself. Spokespeople for Pfizer, BioNTech, and Johnson & Johnson did not immediately respond to requests for comment.

The cases add to an already crowded legal landscape surrounding the blockbuster COVID-19 vaccines. Among the existing disputes is a lawsuit Moderna filed against Pfizer in 2022, also centred on mRNA technology.

Bayer was not involved in developing COVID-19 vaccines and does not manufacture or sell any version of them. In its filings, the company said it is seeking unspecified monetary damages but is not seeking an injunction blocking the companies from making or distributing their vaccines.

Despite declining demand since the height of the pandemic, COVID-19 vaccines remain a significant business. Pfizer and BioNTech reported more than US$3.3 billion in revenue from global sales of their jointly developed Comirnaty vaccine in 2024. Moderna earned $3.2 billion from its Spikevax vaccine over the same period, according to company reports. Johnson & Johnson stopped selling its COVID-19 vaccine in the United States in 2023.

Bayer's lawsuits argue that Monsanto researchers pioneered key techniques in the 1980s aimed at reducing mRNA instability to create more pest-resistant crops. The company alleges that Pfizer and Moderna later used similar methods to improve the stability of mRNA in their vaccines, thereby infringing one of Bayer's patents.

The outcome of the cases could have broader implications for how foundational biotechnology research is applied across industries, particularly as mRNA technology expands beyond vaccines into treatments for cancer and other diseases