Author: Ying Zhang
Background: The 2009 H1N1 outbreak provides an opportunity to identify strengths weaknesses of disease surveillance
notification systems that have been implemented in the past decade.
Methods: Drawing on a systematic review of the scientific literature, official documents, websites, news reports, we
constructed a timeline differentiating three kinds of events: (1) the emergence spread of the pH1N1 virus, (2) local
health officials’ awareness understanding of the outbreak, (3) notifications about the events their implications.
We then conducted a ‘‘critical event’’ analysis of the surveillance process to ascertain when health officials became aware of
the epidemiologic facts of the unfolding pandemic whether advances in surveillance notification systems hastened
Results: This analysis revealed three critical events. First, medical personnel identified pH1N1in California children because
of an experimental surveillance program, leading to a novel viral strain being identified by CDC. Second, Mexican officials
recognized that unconnected outbreaks represented a single phenomenon. Finally, the identification of a pH1N1 outbreak
in a New York City high school was hastened by awareness of the emerging pandemic. Analysis of the timeline suggests
that at best the global response could have been about one week earlier (which would not have stopped spread to other
countries), could have been much later.
Conclusions: This analysis shows that investments in global surveillance notification systems made an important
difference in the 2009 H1N1 pandemic. In particular, enhanced laboratory capacity in the U.S. Canada led to earlier
detection characterization of the 2009 H1N1. This includes enhanced capacity at the federal, state, local levels in
the U.S., as well as a trilateral agreement enabling collaboration among U.S., Canada, Mexico. In addition, improved
global notification systems contributed by helping health officials underst the relevance importance of their own