Vaccine-maker BioNTech faced Monday its first legal claim in its home country of Germany over adverse effects allegedly suffered by some users of its Covid vaccines, more than two years after one of the world's fastest and most extensive inoculation campaigns.

In the face of the deadly pandemic that emerged in early 2020, which prompted border closures and lockdowns that trapped millions of people in their homes, the arrival of Covid vaccines had been widely hailed as a life-saver.

But the jabs, which had been developed at breakneck speed and granted early approval for usage, are now the focus of legal procedures in several countries including France and Britain where plaintiffs argue that the vaccines harmed their health.

In Germany, a court in Hamburg was prepared to hear a case from Monday against BioNTech, which, together with US giant Pfizer, produced the first mRNA vaccine Comirnaty.

The hearing was delayed however after the claimant's lawyers put in a last-minute challenge of the judge's impartiality, and asking instead for a panel of judges to rule on the case.

In her claim, the plaintiff reported suffering effects including "pain in the upper body, swelling of the extremities, exhaustion, fatigue and sleeping disorders" after receiving the vaccine, the court said.

She is seeking 150,000 euros ($162,000) in damages and recognition that the "defendant is bound to provide material damages", the court added.

Her lawyer Thomas Ulbrich, who is also representing another 250 people in similar cases, said his clients were "all healthy" before suffering from symptoms, allegedly following their jabs.

He believes that the medical files he has on hand offer a link between the vaccines and the symptoms experienced by his clients.

'Rocky and long road' 

BioNTech's mRNA vaccine, a scientific breakthrough, had been granted conditional marketing authorisation as early as December 21, 2020, by the EU regulatory authority EMA.

Similar authorisation for Moderna, another mRNA vaccine maker, swiftly followed.

With fears of catching the disease running high, the vaccines were pre-ordered by governments even during their development phases, and deployment swiftly followed once regulatory authorities gave their approval.

But the new generation of inoculations also sparked a wave of vaccine sceptics questioning the safety of the jabs.

Out of 192 million jabs given in Germany, the country's medicines regulator, the Paul Ehrlich Institute, said 338,857 suspected cases of side effects were reported, including 54,879 severe reactions.

Among the worst cases, "the symptoms are very different, they vary from stroke to thrombosis to cardiac diseases", said another German lawyer, Joachim Caesar-Preller, who represents 140 clients making similar claims.

He is seeking up to one million euros in damages per case -- plus interest -- but concedes that a "rocky and long road" lies ahead in the legal battles.

'Not an isolated case' 

A key point for the courts is whether the side effects of the medication, when used correctly, surpass "a justifiable level according to the findings of medical science".

In other words, the effects have to be sufficiently serious to be taken into account, said Anatol Dutta, a professor at Munich University.

A claimant identified only as Kathrin K., 45, believes her symptoms are severe enough.

She said she lost a lot of weight after taking the vaccine and had to undergo several intestinal operations.

"I hate it when people tell me that I'm an isolated case," she said. "I'm not."

To address the question of causality, the courts would likely have to obtain expert advice.

Besides the legal avenue, claimants can also turn to the state for compensation for the loss of income.

More than 8,000 such applications had been made as of April, and so far about five percent have been successful, according to German media.

BioNTech told AFP that the number of liability claims made to the company is very small when compared to the number of doses it has delivered worldwide, and that each claim had to be examined individually.

"Justified liability claims would of course be met by BioNTech," it said, adding however that "no causal relationship between (the) health impairments presented and vaccination with Comirnaty has been proven" in the cases it had reviewed so far.

Another lawyer, Anja Dornhoff, advises her clients to establish a chronology and to get medical practitioners to document the development of their symptoms.

"I hope that people with post-vaccination syndromes can be taken seriously," she said.