Seen a sick face? Your immune system is already working.

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New research has discovered an innate defense mechanism: you don't even have to ingest a virus for your body to get to work. Someone who looks sick is reason enough for your immune system to get moving.

This is evident from a study conducted by the University of Lausanne. The brain appears to recognize visual signals of illness and therefore triggers a series of defense mechanisms. Without you even coughing.

For the study, young adults were given VR headsets. Faces appeared on the screen, gradually moving closer. Some faces looked ill: think coughing, spots, or a runny nose. Others looked neutral or anxious. The results showed that participants reacted more quickly when their faces were touched after seeing an ill face. Their bodies were immediately put on high alert.

Researchers observed in brain scans that areas that monitor personal space and threat responded differently to sick faces than to healthy or neutral faces. "These two systems were activated differently by a sick face, even compared to a fearful face," says neuroscientist Andrea Serino, who was involved in the study.

Perhaps most striking was what happened in the blood. Participants who had seen sick faces showed an increase in certain immune cells: the so-called innate lymphoid cells. These cells are part of the innate immune system and are a kind of first responder of your immune system : they sound the alarm as soon as danger threatens.

The researchers hadn't expected these types of cells to become active without a virus or bacterium actually being present in the body. They even compared the response to what happens after a flu shot and found several similarities. For example, the innate lymphoid cells also reacted first after receiving a flu shot, and in both cases, they began to emit signals that alerted other parts of the immune system.

Admittedly, practical applications are still a long way off, but it opens doors. Perhaps in the future you could temporarily boost your immune system via virtual reality. "Perhaps virtual reality could enhance your immune response in the future and protect you from the flu ," the researchers speculate.

However, the researchers caution that we still don't know everything. "The analysis of the immune response is quite basic," says immunologist Filip Swirski. Little is known about how long the effect lasts and whether it also works in the elderly or other groups.