Researchers study variability in individual vaccine immune responses

Researchers are investigating why individuals experience varying levels of immune reactivity following vaccination. While common side effects like local inflammation, fatigue, or fever result from the immune system learning to recognize antigens, the biological mechanisms driving individual differences remain not fully understood.

Studies have indicated that even among healthy individuals, approximately 5% to 6% may produce a weaker antibody response than average. One key finding suggests that ‘sentinel antibodies’—defenses already present in the blood from previous exposure to common viruses like the common cold—can serve as predictors for how strongly a person will respond to new vaccines, such as those for COVID-19.

Research led by the University of Geneva is specifically looking into these variations in reactogenicity to better understand why some people experience mild symptoms while others face more pronounced, flu-like reactions.