Dr Michelle Dickinson: Nanotechnologist on whether seeing an ill person can trigger your immune system - The Sunday Session with Francesca Rudkin

Have you ever instinctively taken a step back when someone sneezes near you on the bus? It turns out that your body may be doing more than just helping you avoid germs, it might be quietly powering up your immune system too. 

In a new study published this week in Nature Neuroscience, researchers found that even the sight of someone who looks contagious can kickstart a biological response in your body. 

In the study, virtual reality headsets were placed on 248 healthy participants who were shown videos of people who appeared either neutral, fearful, or visibly sick (with skin rashes or other infection-like cues). These virtual people slowly moved closer to the participants in the simulation. 

In one experiment, participants had to press a button as quickly as possible after being lightly touched on the face. When the 'sick' characters appeared, people reacted as if the faces were physically closer, even when they were further away. Their brains and bodies were responding as though a threat had entered their personal space. 

Brain scans showed increased activity in regions associated with detecting threats and regulating body responses. 

Even though no real germs were involved, researchers found from blood test results that there were changes in immune cell activity when people viewed the sick-looking characters. Specifically, they saw an uptick in innate lymphoid cells, a type of immune cell known to act as first responders, alerting the rest of the immune system to potential trouble. 

This reaction was so real that it mirrored what researchers see in people who’ve just had a flu shot, without any actual virus exposure. 

Your instinct to avoid someone who looks unwell isn’t just common sense, it might be part of a deeply wired, whole-body reaction designed to protect you 

So next time you see someone sniffling on the train, don’t just trust your gut, know that your body might already be gearing up for battle. 

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