Why vaccine responses vary from person to person

Although vaccinations are one of the most effective public health measures for preventing infectious diseases, not everyone receives the same amount of protection.

Many factors determine whether an individual responding to vaccination will generate an effective response, including specific biomarkers within a person's immune system, but until now there has been no evidence showing whether these factors were universal across a wide range of vaccines.

New findings from a meta-analysis published in Nature Immunology examine the biological mechanisms responsible for why some people's immune systems respond differently to vaccinations, which could have global implications for the development and administration of vaccines.

As part of a series of studies for The Human Immunology Project Consortium (HIPC), a network of national research institutions studying the range of responses to different infections and vaccinations, Emory researchers analyzed the molecular characteristics of 820 healthy young adults who were immunized with 13 different vaccines to identify specific biomarkers that generate antibody response to vaccines.

The participants were separated into three endotypes, or groups with a common gene expression, based on the level of inflammatory response prior to vaccination -- a high-inflammatory group, a low-inflammatory group, and a mid-inflammatory group. After studying the immunological changes that occurred in participants following vaccination, researchers found the group that had the highest levels of inflammation prior to the vaccine had the strongest antibody response.

"We were surprised because inflammation is usually depicted as something that is bad," says Slim Fourati, PhD, bioinformatic research associate at Emory University and first author on the paper. "These data indicate that some types of inflammation can actually foster a stronger response from a vaccine."

Fourati, Dr Rafick-Pierre Sekaly, professor and senior author of the paper, and the HIPC team identified specific biomarkers among this group and cellular features that characterized the pre-vaccination inflammatory signature, information that can be used to predict how well an individual will respond to a vaccine.

"With the knowledge, we now have about what characteristics of the immune system enable a more robust response, vaccines can be tailored to induce this response and maximize their effectiveness," says Fourati. "But we still have more questions to answer."

More research is needed to determine the cause of this inflammation in otherwise healthy adults. Additionally, Fourati suggests future studies should look at how these biomarkers facilitate vaccine protection in older age groups and among populations who are immunocompromised.