BioNTech, the German vaccine maker behind the widely used COVID-19 vaccine, is set to appear in court on Monday as it defends itself against the first lawsuit in Germany related to alleged side effects of its vaccine.

The plaintiff, who remains anonymous under German privacy law, is seeking damages of at least 150,000 euros ($161,500) for bodily harm and unspecified material damage. The woman claims to have experienced upper-body pain, swollen extremities, fatigue and sleeping disorders following vaccination, Reuters reported.

BioNTech, in its response, maintained that the case lacks merit, emphasizing the positive benefit-risk profile and well-characterized safety profile of its vaccine, Comirnaty.

"The positive benefit-risk profile of Comirnaty remains positive, and the safety profile has been well characterized," BioNTech stated.

The lawsuit raises questions about the risk-benefit assessment of the BioNTech shot, with the plaintiff's lawyer, Tobias Ulbrich, aiming to challenge the conclusions reached by European Union regulators and German vaccine assessment bodies.

Under German pharmaceutical law, manufacturers are liable for damages caused by side effects if medical science demonstrates disproportionate harm relative to benefits or if label information is incorrect.

In a separate development, biotech firm Promosome has filed lawsuits against Moderna, Pfizer and BioNTech in a California federal court, alleging patent infringement related to messenger RNA (mRNA) technology used in COVID-19 vaccines. Promosome seeks a share of royalties from vaccine sales.

Last year, Pfizer reportedly earned $37.8 billion from its COVID-19 vaccine Comirnaty, while Moderna made $18.4 billion from its vaccine Spikevax.

This legal action adds to the ongoing litigation faced by Pfizer and Moderna, as Alnylam Pharmaceuticals Inc. also sued them last month, claiming a violation of its intellectual property rights in lipid nanoparticle (LNP) technology, which is integral to the delivery mechanism of the mRNA COVID-19 vaccines.

These lawsuits highlight the legal challenges faced by vaccine manufacturers as they navigate claims related to side effects and intellectual property infringement in the context of the global vaccination effort against COVID-19.