AIDS is the fourth worst infectious disease of all time, resulting in more deaths per day over the past 25 years than occurred on 9/11/2001 [35] . Over 33 million adults are now infected with HIV, many in the developing world, where resources are scarce and infrastructure is struggling under the weight of this burgeoning epidemic. The HIV/ AIDS epidemic is often spoken of in terms of "reducing the spread" [36] , or achieving "sustainable financing" [37] However, this special issue demonstrates that, despite the immensity of the epidemic, eradication is not only possible, it is feasible. The time has come to stop thinking locally and to start acting globally. Early Assessment of Anxiety and Behavioral Response to Novel Swine-Origin Influenza A(H1N1) BACKGROUND: Since late April, 2009, a novel influenza virus A (H1N1), generally referred to as the “swine flu,” has spread around the globe and infected hundreds of thousands of people. During the first few days after the initial outbreak in Mexico, extensive media coverage together with a high degree of uncertainty about the transmissibility and mortality rate associated with the virus caused widespread concern in the population. The spread of an infectious disease can be strongly influenced by behavioral changes (e.g., social distancing) during the early phase of an epidemic, but data on risk perception and behavioral response to a novel virus is usually collected with a substantial delay or after an epidemic has run its course. METHODOLOGY/PRINCIPAL FINDINGS: Here, we report the results from an online survey that gathered data (n = 6,249) about risk perception of the Influenza A(H1N1) outbreak during the first few days of widespread media coverage (April 28 - May 5, 2009). We find that after an initially high level of concern, levels of anxiety waned along with the perception of the virus as an immediate threat. Overall, our data provide evidence that emotional status mediates behavioral response. Intriguingly, principal component analysis revealed strong clustering of anxiety about swine flu, bird flu and terrorism. All three of these threats receive a great deal of media attention and their fundamental uncertainty is likely to generate an inordinate amount of fear vis-a-vis their actual threat. CONCLUSIONS/SIGNIFICANCE: Our results suggest that respondents' behavior varies in predictable ways. Of particular interest, we find that affective variables, such as self-reported anxiety over the epidemic, mediate the likelihood that respondents will engage in protective behavior. Understanding how protective behavior such as social distancing varies and the specific factors that mediate it may help with the design of epidemic control strategies. An ongoing outbreak of novel influenza A(H1N1), colloquially referred to as ''swine flu,'' has caused over 200,000 confirmed cases (as of 28 August 2009 [1] ). Because of under-reporting, the actual number of people infected is substantially larger, particularly considering that many countries have ceased testing for A(H1N1) [1] . As human-to-human transmission became widespread in at least one region of the world, WHO rapidly declared the outbreak an imminent pandemic [2] and with widespread human infection, WHO declared a phase 6 pandemic on 11 June 2009, where it remains at the time of submission [3] . The virus appears to have a higher reproduction number and somewhat higher case fatality ratio than recent seasonal influenza viruses [4, 5] , and has certainly caused great concern in the population, fueled by both extensive media coverage and an initially high level of uncertainty about mortality rates and transmissibility of the virus.