09/04/2025
Just the sight of a sick person can trigger our immune system — even if they’re just a virtual image on a screen.
In a new study, researchers used virtual reality headsets to show people avatars that looked either healthy or visibly ill, think pale skin, rashes, or feverish faces. What happened next surprised even the scientists: just seeing the “sick” avatars caused participants’ brains to switch into high alert and sent signals to their immune systems. Specifically, certain immune cells in their blood, known to respond during actual infections, increased, despite no physical contact or real illness present. The brain seemed to interpret the visual signs of sickness as a potential threat, and that alone was enough to start a defensive response.
Participants’ reaction times even changed. When they saw a sick-looking avatar and felt a light touch on their face, they responded faster, as if their bodies were bracing for danger. Interestingly, the strongest brain responses came not when the sick avatar was close, but when it appeared farther away, possibly because the brain sees something approaching as more of a threat. Areas of the brain like the hypothalamus lit up, this is the same region that gets activated when we’re vaccinated or exposed to certain immune triggers. The researchers say this suggests our brains and immune systems are more tightly connected than we thought. It’s not just about catching a virus, it’s about sensing the possibility of one. This fast-acting, built-in alert system may be a leftover from evolution, helping humans spot and avoid illness before it spreads.
paper
Trabanelli, S., Akselrod, M., Fellrath, J. et al. Neural anticipation of virtual infection triggers an immune response. Nat Neurosci (2025).
