- Correspondence to: Emily J Tweed, University of Oxford, c/o Lisa Brant, Health Protection Agency Centre for Infections, 61 Colindale Avenue, Colindale, London, NW9 5EQ, United Kingdom;
- Received March 2, 2009
- Accepted September 25, 2009
- First published October 26, 2009.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.