Experts have been warning for several years now, that the next influenza pandemic is bound to happen in the relatively near future. However, the exact timing cannot be predicted. With these thoughts in mind, I attended a symposium titled “Influenza: New Strains and New Approaches” on October 31, 2004, during the 44th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in Washington, D.C. I was impressed by the information provided and would like to use this editorial to share this information with our readers. I think that the topic is very important and that the infectious diseases community and public officials are not sufficiently prepared to deal with the troubles ahead. The following paragraphs are based on the notes, which I took during the presentations and contain my personal recollection of the main points made by each of the presenters. Klaus Stohr (WHO, Geneva) first talked about the global burden of influenza. He pointed out that events with pandemic potential had accelerated recently. Since last year a series of epidemics caused by H5N1 have occurred in nine countries. These animal outbreaks have also involved a series of human cases. The pathogenicity of H5N1 has increased in chickens and tigers have been infected by this strain as well. The prevalence of H5N1 in pigs is unknown. This virus has also been found in domestic ducks in southern China and Thailand without causing disease. Attempts to achieve viral eradication have been unsuccessful and a second wave of infections in chickens occurred during last summer. These observations point to a gathering problem and possibly to a reduction of the barriers for the virus to spread to and among other species. According to Stohr, human disease surveillance in many countries is suboptimal. He urges that the “window of opportunity” to produce sufficient amounts of vaccine and antivirals is now. However, only two companies are currently producing. Yoshihiro Kawaoka of the University of Wisconsin, Madison, Wisconsin, addressed the question: “why influenza kills and will kill again?” During 1918 influenza H1N1 caused 20 million deaths. Using reverse genetics and cloned DNA, his research group was able to show that the hemagglutinin H1 is responsible for pathogenicity of this virus. The virus induces MIP-2 expression in lung tissue, resulting in neutrophil chemotaxis and lung damage. Interestingly, survivors of the 1918 influenza pandemic have long-lasting and high antibody titers. This is interpreted as a cross-reaction of the immune system to other, more recently used vaccines. Both Kawaoka and Frederick Hayden (University of Virginia, Charlottesville, VA) spoke about viral resistance. According to Kawaoka, 30% of strains may develop resistance to amantadine. This may happen within days of amantadine treatment, as various mutations may occur simultaneously. Kawaoka reported that approximately 80% of pediatric patients who were treated with amantadine developed resistance. Development of resistance has also been reported in 18% of pediatric patients treated with oseltamivir. Mutations resulting in modifications of neuraminidase are associated with a more than 100,000-fold decrease of susceptibility of affected viral strains. Hayden summarized the data on the use of amantadine and newer antiviral agents in prophylaxis and treatment of influenza. The protective effect of amantadine is approximately 70%, 84% for zanamivir and oseltamivir. Both, zanamivir and oseltamivir protect 73 to 89% of exposed persons, if used as postexposure prophylaxis. They prevent 80% of secondary cases in households with an index case. These agents reduce viral load and duration of symptoms, if used to treat patients with symptomatic influenza infection. Development of resistance is a problem which has been observed with both agents. Oseltamivir resistance was registered in 0.4% of adult outpatients, 5.5% of pediatric outpatients, and 18% of hospitalized children. Based on these data, Japanese researchers apparently proposed the concept of “ring-tamifluation” in case of the emergence of human cases of H5N1 infection. According to Hayden, these antiviral agents should be used for priority groups, including front-line workers, public safety personnel, hosInfection Editorial