Boys infect boys with swine flu

A new study of how swine flu spread in a primary school during the 2009 pandemic has revealed that boys predominantly pass on flu to other boys and girls to girls.

The results also suggest that flu transmission is most intensive between children of the same class, but that sitting next to an infected person does not significantly increase a child`s risk of catching flu.

In the study, researchers from Imperial College London, the US Centers for Disease Control and Prevention (CDC) and the Pennsylvania Department of Health analysed how social networks influenced the spread of H1N1 pandemic flu in an elementary school in Pennsylvania.

The results show that children are about three times more likely to transmit flu to children of the same gender than to children of the opposite gender.

The researchers also found that the transmission rate is about five times higher between classmates than between children in a different class in the same grade, and about 25 times higher than between children in different grades.

The researchers collected extensive data from seating charts, school timetables, bus schedules, nurse logs, attendance records and questionnaires.

"Mathematical models are useful for predicting how outbreaks will spread, but in order to make the models accurate, we need to supply them with data about how disease spreads in the real world," said Simon Cauchemez, the lead author of the study.

"The data from this study will help us make more accurate models, which can help public health officials to handle epidemics effectively. For example, these new models could help us better understand whether and when it would be appropriate to close a school, or whether it might be better to close individual classes or grades," said Cauchemez.

The findings were published in the journal Proceedings of the National Academy of Sciences .