Can looking at someone sneezing boost your immune system?

Surprisingly, yea. Mark Schaller from the University of British Columbia found that people who see images of sneezes and other signs of disease mount a stronger immune response to later infections than people who see unrelated images. It seems that looking at someone sneezing primes our immune system to prepare for battle.

This is the first evidence that the mere sight of a possible infection, even through a photograph, can set our bodies’ defences on high alert.

Previously, Schaller has suggested that the visual signs of disease trigger a variety of psychological tics that reduce our chances of infection. A disgusted reaction fulfils this role by making us less likely to approach potential sources of contagion. Last year, another group showed that a sneezing passer-by can make people more worried about completely unrelated threats, like heart attacks, crime and accidents. To Schaller, these reactions are all part of our “behavioural immune system” – our means of preventing infections by changing our behaviour.

But his latest study suggests that images of sickness can prime our actual immune systems too. He recruited 28 volunteers, split them into two groups, and showed them two slide shows. The first slides were just shots of furniture. The second set showed either signs of infectious diseases, such as pox, skin lesions or sneezing, or images of people brandishing guns, mostly aimed directly at the viewers.

This suggests that the immune system reacts with extra vigour after its owner sees an image specifically related to disease, rather than one that invokes a general sense of threat or danger.

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