The patent infringement lawsuits said the companies copied technology developed by Monsanto in the 1980s for strengthening mRNA in crops in order to stabilise the genetic material used in their vaccines.

Bayer separately filed a similar lawsuit against Johnson & Johnson in New Jersey federal court on Tuesday, arguing that a DNA-based process J&J used in manufacturing its shots infringed the patent.

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.

Bayer’s complaints add to a web of patent lawsuits over the blockbuster Covid shots, which include an ongoing lawsuit filed by Moderna against Pfizer in 2022.

Bayer was not involved in developing Covid vaccines and does not make or sell any version of them. It asked the courts for an unspecified amount of monetary damages and said it was not seeking to block the companies from manufacturing their vaccines.

Pfizer and BioNTech earned more than US$3.3 billion in revenue from global sales of their vaccine Comirnaty in 2024, while Moderna earned US$3.2 billion from its Spikevax, according to company reports, a fraction of their sales at the height of the pandemic.

Johnson & Johnson stopped selling its Covid vaccine in the United States in 2023.

Bayer’s lawsuits said Monsanto scientists pioneered technology in the 1980s for reducing mRNA instability to make more pest-resistant crops. Bayer alleged that Pfizer and Moderna utilised technology for improving the stability of mRNA that infringes one of its patents.