Moderna has sued Pfizer alleging its largest competitor ripped off their version of the COVID-19 vaccine. Moderna has filed a patent infringement lawsuit claiming Pfizer is using its patented mRNA technology. Moderna wasn’t going to enforce the patent during the pandemic.

“Moderna refrained from asserting its patents earlier so as not to distract from efforts to bring the pandemic to an end as quickly as possible,” the company said in a statement. Moderna still does not plan on enforcing the patent in low-income countries. They are coming after Pfizer and BioNTech, which Moderna said they are expected to “respect its intellectual property rights.”

In the legal filing, Moderna alleged that Pfizer copied two elements. The first is a chemical modification to the mRNA. The second is the bit of the virus that the vaccines are using. Both companies target the full coronavirus spike protein. Moderna said in its legal filing that it got a patent for vaccines using the full spike protein after their own research on MERS, another type of coronavirus. Moderna said they invested billions of dollars into their research and making of the COVID-19 vaccine and want to be compensated for it.

Now that the pandemic has slowed, Moderna wants to be paid. They’re not looking to take Pfizer’s vaccine off the shelf but they want a cut from their doses administered from here on out. It is common for vaccine companies to come after each other. Pfizer and Moderna both are facing several other lawsuits on similar grounds. The timing comes as the federal government will soon stop footing the bill for vaccinations.