Coughs and sneezes spread diseases, but before things even get that far scientists have found we can tell when someone is sick at a glance.
A new study published by the Royal Society observed that humans can spot signs of illness just from a brief glimpse of someone's face, even just hours after they're infected.
Scientists injected people with E.coli bacteria to bring on flu-like symptoms, then showed a picture of the subject to 62 study participants for a couple of seconds. 70 per cent of the time they were able to spot who was healthy.
Participants identified subtle facial cues in unwell people including pale lips and skin, a swollen face or drooping mouth, hanging eyelids and redder eyes.
However scientists suggest a larger study would be helpful, according to the Guardian.