People who carry a version of an HLA gene known as HLA-DQB1*06 are more likely to generate a higher antibody response after getting their vaccination than those who do not, researchers found.
The team said their findings, published in the journal Nature Medicine, could in future improve vaccines and help prevent infection.
“We have seen a wide variation in how quickly people test positive for Covid-19 after vaccination,” said Dr Alexander Mentzer, NIHR academic clinical lecturer at the Wellcome Centre for Human Genetics and a lead researcher on the study.
“Our findings suggest that our genetic code may influence how likely this is to happen over time.
“We hope that our findings will help us improve vaccines for the future so they not only stop us developing severe disease, but also keep us symptom-free for as long as possible.”
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The team analysed DNA samples from 1,190 participants enrolled in the University of Oxford’s vaccine clinical trials, as well as from 1,677 adults who had enrolled on the Com-COV research programme.
They also looked at samples from children who had participated in clinical trials for the AstraZeneca vaccine.
The researchers found individuals carrying the HLA-DQB1*06 gene recorded higher antibody responses against the Covid-19 vaccines at 28 days following the first dose.
Participants who had the gene were also less likely to experience breakthrough infection — where people still get infected with coronavirus despite being vaccinated.
Around 30-40 per cent of people in the UK are thought to carry the HLA-DQB1*06 gene.
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“Further work is needed to better understand the clinical significance of this specific association, and more broadly what identifying this gene variant can tell us about how effective immune responses are generated and ways to continue to improve vaccines for everyone,” said Julian Knight, professor of genomic medicine at the University’s Wellcome Centre for Human Genetics and chief investigator on the study.
The findings come as Covid-19 booster doses become available to over 50s in England on Friday — with 26 million people being eligible for the autumn jab.
A majority of them will be offered the newer bivalent vaccine which targets the original Covid-19 variant and the newer Omicron one.