By Michelle Roberts for BBC
A healthcare worker member draws up a syringe with the BioNTech, Pfizer vaccine adapted to the Omicron-BA.1 variant. Photo: Sebastian Gollnow / DPA / dpa Picture-Alliance via AFP
A 62-year-old man from Germany has, against medical advice, been vaccinated 217 times against Covid, doctors report.
The bizarre case is documented in The Lancet Infectious Diseases journal.
The shots were bought and given privately within the space of 29 months.
The man appears to have suffered no ill effects, researchers from the University of Erlangen-Nuremberg say.
'Very interested'
"We learned about his case via newspaper articles," Dr Kilian Schober, from the university's microbiology department, said.
"We then contacted him and invited him to undergo various tests in Erlangen. He was very interested in doing so."
The man provided fresh blood and saliva samples.
The researchers also tested some frozen blood samples of his that had been stored in recent years.
Schober said: "We were able to take blood samples ourselves when the man received a further vaccination during the study at his own insistence.
"We were able to use these samples to determine exactly how the immune system reacts to the vaccination."
Evidence for 130 of the jabs was collected by the public prosecutor of the city of Magdeburg, who opened an investigation with the allegation of fraud, but no criminal charges were brought.
Covid vaccines cannot cause infection but can teach the body how to fight the disease.
Immune system
Messenger ribonucleic acid (mRNA) vaccines work by showing the body's cells a bit of genetic code from the virus.
The immune system should then recognise and know how to fight Covid should they encounter it for real.
Schober worried hyper-stimulating the immune system with repeated doses might have fatigued certain cells.
But the researchers found no evidence of this in the 62-year-old.
And there was no sign that he had ever been infected with Covid.
'Favoured approach'
The researchers said: "Importantly, we do not endorse hyper-vaccination as a strategy to enhance adaptive immunity."
And the results of their tests on the 62-year-old were insufficient for making far-reaching conclusions, let alone recommendations for the general public.
"Current research indicates that a three-dose vaccination, coupled with regular top-up vaccines for vulnerable groups, remains the favoured approach," they say on the university's website.
"There is no indication that more vaccines are required."
The NHS says Covid vaccines are normally given seasonally but some people with a severely weakened immune system may need additional protection at other times - and it will contact those whose NHS record suggests may be eligible.
Covid vaccines can have side effects. A common one is a sore arm from the injection.
- This story was first published by BBC.