With friends like these . . .

IT MAY come as a disappointment to hear this, but your friends are probably more popular than you are. New research has found that this “friendship paradox” may help predict the spread of infectious disease.

The friendship paradox states that if you take a random group of people and ask each of them to name one friend, the named people will rank higher in the social web than the ones who named them. On average, people name friends who are well connected and are unlikely to name a recluse.

But the popular people pay a price. Just as they get the gossip and the trends first, they also pick up the flu first, on average two weeks sooner than most others, research in the Public Library of Science journal PLoS ONEhas found.

“Being at the centre of the network tends to make you happy, but it also exposes you to disease,” said one of the report authors, Prof James Fowler of the University of California.

He worked with Nicholas Christakis of Harvard University to see if the friendship paradox could help work out how flu pandemics and other viruses are likely to behave.

As the flu season approached last autumn, they contacted 319 Harvard undergraduates, who in turn named 425 friends.

Monitoring the groups in the months that followed, they found that, on average, the friends group manifested the flu between two and seven weeks before the random group.

“We think this may have significant implications for public health,” Prof Fowler said.

“By simply asking members of the random group to name friends, and then tracking and comparing both groups, we can predict epidemics before they strike the population at large.

“If you want a crystal ball for finding out which parts of the country are going to get the flu first, then this may be the most effective method we have now,” he said.

“We show a way you can get ahead of the epidemic of flu, or potentially anything else that spreads in networks.”

The Google Flu Trends service is also using the internet to trace flu outbreaks. It has found a close relationship between how many people search for flu-related topics and how many people have flu symptoms. Its results have been published in the journal Nature.

Prof Fowler and Prof Christakis are experts on social networks. They have worked on studies that show how obesity and smoking are directly related to a person’s friends, and the friends of their friends.