The first comprehensive study of pandemic H1N1 influenza from April to the end of July indicates that the pandemic may be the mildest ever, assuming that the virus doesn't mutate during the winter and come back stronger than before. The analysis suggests that the swine flu virus might directly cause as many as 45,000 deaths in the United States by the end of winter but that the most likely figure is somewhere between 10,000 and 15,000 deaths. In a worst-case scenario, the virus would kill no more than 45,000 people, well below earlier estimates that suggested as many as 90,000 could die in the pandemic.
A typical flu season is associated with about 35,000 deaths. In 1957, the Asian flu pandemic killed about 70,000 Americans. Making accurate projections about the course of a pandemic is difficult, both because the virus itself is so unpredictable and because it is hard to obtain accurate estimates of the total number of people infected. In the new study, a team led by epidemiologist Mark Lipsitch of the Harvard School of Public Health studied data collected in New York City and Milwaukee, which have some of the most effective surveillance programs available. They reported their results in the journal PLoS Medicine.