Researchers identify biological markers for vaccine response and side effects

Recent studies are uncovering biological markers that may predict how individuals react to vaccines. Researchers at the University of Geneva and Geneva University Hospital investigated the drivers behind the varying severity of transient side effects, such as fatigue and fever, following mRNA COVID-19 vaccinations.

The study, published in Science Translational Medicine, found that an individual’s baseline innate immunity plays a critical role. Specifically, people with a naturally higher interferon-related antiviral response—signaling molecules that alert the body to viral infections—experienced more pronounced temporary side effects.

In a separate study led by Arizona State University and published in Cell Press, researchers identified that pre-existing antibody patterns, termed ‘sentinel’ antibodies, may indicate how strongly a person will respond to a vaccine. By analyzing blood samples from over 4,000 participants, the team found that higher levels of antibodies against other microbes, such as Staphylococcus aureus and certain respiratory viruses, were linked to stronger responses to COVID-19 vaccination. These findings suggest that previous immune encounters leave measurable patterns that could help identify individuals at risk of a blunted immune response.