Moderna filed a lawsuit against Pfizer and its German partner BioNTech on Friday for patent infringement in developing the first COVID-19 vaccine approved in the United States, claiming they copied the technology developed by Moderna years before the pandemic.

Pzifer's shares fell by about 1 percent, while the shares of U.S.-listed BioNTech dropped about 1.5 percent, and Moderna's shares fell 1.7 percent on Friday.

The lawsuit, seeking unspecified monetary damages, was filed in the U.S. District Court in Massachusetts. In a press release issued on Friday, Moderna said the lawsuit will also be filed in the District Court of Dusseldorf in Germany.

Stefan Bancel, CEO of Moderna, said in the press release: "We are filing these lawsuits to protect the mRNA technology platform we invented, invested billions of dollars in creating, and obtained patents for during the decade before the COVID-19 pandemic."

Just a decade ago, Moderna, based in Cambridge, Massachusetts, was an innovator in mRNA vaccine technology that enabled unprecedented speed in developing the COVID-19 vaccine, and the approval process that used to take years was completed in months, largely thanks to the breakthrough in mRNA vaccines, which teach human cells how to make a protein that triggers an immune response. Germany-based BioNTech was also working in this field when it partnered with the American pharmaceutical giant Pfizer.

The U.S. Food and Drug Administration first granted emergency use authorization for the COVID-19 vaccine to Pfizer/BioNTech in December 2020, and then one week later to Moderna.

Moderna's COVID vaccine — its only commercial product — generated revenues of $10.4 billion this year, while Pfizer's vaccine earned about $22 billion. The lawsuit is likely to take years to resolve, according to Cowen & Co. analyst Tyler Van Buren, as Moderna alleges that Pfizer/BioNTech copied the mRNA technology patented by Moderna between 2010 and 2016 without permission, before COVID-19 emerged in 2019.

Pfizer and BioNTech are already facing multiple lawsuits from other companies claiming the partnership's vaccine infringes their patents.