A team of UK researchers has found a pattern in gene-expression immune cells that could help doctors predict which people are likely to have adverse responses to vaccinations.

According to a paper published in the journal Nature Immunology, the team studied the response to flu vaccinations in 178 healthy adults in the UK and sifted out some of the gene-expression immune cells that were responsible for adverse reactions.

The research group found that approximately 20% of those vaccinated experienced an adverse response to some degree—the team focused their efforts on these people, looking at changes in the immune response, as compared to those who did not experience an adverse reaction. They also monitored white blood cell counts and gene expression in other blood cells.