COVID-19 vaccine maker Moderna is suing Pfizer and the German drugmaker BioNTech, accusing its main competitors of copying Moderna’s technology in order to make their own vaccine.

Moderna said Friday that Pfizer and BioNTech’s vaccine Comirnaty infringes on patents Moderna filed several years ago protecting the technology behind its preventive shot, Spikevax. The company filed patent infringement lawsuits in both U.S. federal court and a German court.

A Pfizer spokeswoman declined to comment, saying the company had not been served with a copy of the litigation.

Moderna and Pfizer’s two-shot vaccines both use mRNA technology to help patients fight the coronavirus.

The mRNA vaccines work by injecting a genetic code for the spike protein that coats the surface of the coronavirus. That code, the mRNA, is encased in a little ball of fat, and instructs the body’s cells to make some harmless spike copies that train the immune system to recognize the real virus.

Moderna CEO Stephane Bancel said in a prepared statement that the vaccine developer pioneered that technology and invested billions of dollars in creating it.

The company said it believes its rivals’ vaccine infringes on patents Moderna filed between 2010 and 2016.