The Brain Activates the Immune System When Sick People are Nearby

Rise of Virtual Reality in Healthcare

Virtual Reality (VR) games are becoming more popular due to their immersive and almost real-life experiences. In healthcare, VR is being increasingly used in medical training. For instance, VR has been shown to improve surgical precision and prepare for responding to medical emergencies. Recently, researchers used VR headsets to explore neuro-immune mechanisms in the human body.¹

They asked a simple question: What happens to our immune cells when we see a sick or diseased person? To investigate this, participants viewed images of people with obvious signs of infection approaching them through a VR headset.

Behavioral Immune System

Humans have developed psychological mechanisms to prevent infections and other threats. This serves as a first line of defense, even before our immune system interacts with disease-causing agents, and is known as the behavioral immune system. These mechanisms are part of our daily routines, such as practicing good hygiene, letting colleagues work from home if they feel sick, or practicing social distancing during a pandemic - a form of avoidance.

Decoding a Neuro-Immune Connection

Given our general understanding of the behavioral immune system, details about the specific brain regions involved and the subsequent immune response to potential visible threats remain unclear. Therefore, Trabanelli and colleagues conducted an exploratory analysis by exposing healthy participants to VR avatars of infectious people. Avatars were made to approach the participants without touching them, activating specific regions in the brain that perceived personal space.

The Study

Participants were divided into four cohorts: three groups were exposed to VR avatars displaying neutral, infectious, or violent traits. The fourth group was not exposed to VR avatars; instead, they received the flu vaccine (Fig 1). This setup allowed researchers to control for perceptions of non-infectious or harmless exposure and to compare them with immune responses to a vaccine.

Brain scans were conducted as the avatars approached the participants. Blood was drawn immediately afterward to assess immune cell activity, focusing on Innate Lymphoid Cells (ILCs).

Fig 1: Details Of The Experimental Groups

The Results - a Neuro-Immune Link

Researchers observed that both virtual (VR avatar showing an infected avatar approaching) and real infections (influenza vaccine) elicited similar immunological patterns. The activation profile of ILCs was also comparable in the two groups, indicating a preemptive immune response. A virtual infection activates areas of the brain responsible for personal space regulation, which remain inactive when exposed to neutral avatars.

Conclusion

These results shed light on a complex cross-talk between the brain and our immune system. It is reassuring to know that we probably evolved to mount an immune response and be defense-ready even before physically encountering an invader. This study suggests a potential strategy to improve our immunity. For instance, could we use VR headsets before getting vaccinated to trigger a stronger immune response?

With all these potential benefits, there are also larger questions. This research was exploratory and only involved young adults. Since immune responses decline with age, could this method be effective in other age groups? Questions about how long elevated immune responses last also remain. Nonetheless, this is an exciting time for neuro-immunology. We are getting closer to understanding how our bodies remarkably detect disease-causing agents and coordinate responses to ensure survival.

References

1.          Trabanelli, S. et al. Neural anticipation of virtual infection triggers an immune response. Nat Neurosci 1–10 (2025) doi:10.1038/s41593-025-02008-

Fig 2: Immune System Activation