Fig. 1.

Observed contact pattern data from contact surveys. (A) A peer-group network recorded at Warwick University. Network members are represented by black dots arranged in a circle. Contacts between members represent physical contact (red lines) and conversational nonphysical contact (blue lines). Contacts with individuals outside the peer group (gray dots) are represented by orange lines. (B) Observed spatial distribution of contacts, showing work-based contacts (blue) and physical contacts both in and out of work (red). Both images are based on unpublished data, courtesy of John Edmunds (Health Protection Agency, London, U.K.). The image in A is courtesy of Jonathan Read (Warwick University, Coventry, U.K.).