Hot Topics in Respiratory Medicine - Editor-in-chief: Marc Miravitlles

The 21^st Century is the era of globalization. People can travel between countries and continents in a matter of hours or days, and, with those people, infective agents can also be disseminated at unprecedented speeds.
One example is the influenza A (H1N1) virus. Since the first alarm in Mexico in early 2009, the pathogen spread quickly worldwide such that in less than 2 months 160 countries experienced both mild and severe disease caused by the new virus. National and international health agencies responded quickly, amassing and transmitting detailed scientific knowledge of this new pandemic. Six months was sufficient time to understand the clinical behavior of the disease and its severity worldwide.
This issue of Hot Topics in Respiratory Medicine is dedicated to this new pandemic. As of November 15, 2009, there were approximately 622,000 laboratory-confirmed cases of pandemic influenza A (H1N1) worldwide, including at least 7826 deaths. Using mathematical modeling, the United States Centers for Disease Control and Prevention (CDC) has estimated that around 4000 fatal cases occurred in the United States between April 2009 and mid-October 2009.
These figures created alarm in the Northern Hemisphere as winter approached. A massive vaccination campaign was begun at the end of 2009 and, fortunately, the incidence and severity of the influenza have not been as serious as expected. The reasons for this milder disease are not clear, and we still have lessons to learn from the epidemiology of this new virus.
The three articles in this issue provide timely insight into the dissemination of this new strain of influenza A (H1N1) virus, the clinical manifestations of the disease it causes, and the preventive strategies that have helped to reduce the risk of a greater pandemic.
This is one more page in the history of new pandemics. More pandemics will certainly come, so we need to be ready to take action in the future, when the increasing human population and intercontinental travel may facilitate the rapid spread of other, old or new, pathogens around the globe.