21 April 2006
Vol 312, Issue 5772

About The Cover

Cover image expansion

COVER Animal health experts, like this ornithologist in Croatia, are on high alert for signs of H5N1 avian influenza. Despite its rapid spread, H5N1 remains primarily a disease of birds. A special section beginning on page 379 examines obstacles to human-to-human transmission and options for responding to a possible pandemic, such as predictive computer models and "universal" vaccines. Photo: Matko Biljak/Reuters