The body’s immune system can react to seeing others being sick, a new California study finds. Biology Prof. Patricia Lopez researched this and her study, “Responding to infection affects more than just the host,” was published in the journal Trends in Ecology & Evolution. Healthy animals were found to activate molecular pathways related to immune responses and change their egg composition when interacting with sick animals, similar responses are also found in humans. Lopez emphasized that these responses should not replace preventive measures like vaccines. She also called for more awareness and integration of potential off-host effects.