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Health Expert Says Swine Flu Not Likely to Mirror 1918 Pandemic

Researchers in the United States are working furiously to prepare for the upcoming flu season, which usually begins in late October, but could peak earlier than normal this year. Vaccines are being tested to prevent mass outbreaks of H1N1, and the World Health Organization expects large doses to be available in time for flu season. As researchers learn more about the virus, it's being compared to the Spanish influenza pandemic of 1918. The Johns Hopkins Bloomberg School of Public Health is home to some of the leading scientists who are conducting research into the mutating virus and the measures being taken to deal with it.

The World Health Organization confirms nearly 100,000 people around the world have been diagnosed swine flu - or the H1N1 virus. But many epidemiologists say there are likely millions of unconfirmed cases.

Even more people in the Northern Hemisphere will likely get sick this autumn during the influenza season - but it's not yet clear how much of a threat the virus will pose.

Andrew Pekosz is an Associate Professor of Microbiology and Immunology at Johns Hopkins University. He notes that this H1N1 virus strain shares some similarities with the 1918 Spanish influenza pandemic, which is thought to have affected one-third of the world's population, and killed at least 50 million people.

But his studies on the new strain show it's unlikely to follow that path.

"This particular 2009 H1N1 influenza virus is missing some of the very key determinants of virulence, or disease causation, that the 1918 influenza had. Therefore I don't think it's very likely that this virus will mutate to become as deadly as the 1918 influenza was," Dr. Pekosz said.

But he cautions that H1N1 is likely to cause the majority of influenza cases in the Northern Hemisphere this fall.

"If we look to the Southern Hemisphere, which is right now in the middle of their flu season, what we see is that influenza there has started earlier, there are more cases, and the virus is spreading faster than in a normal influenza virus season," Dr. Pekosz said, "And there's no reason for us to not expect the same thing to happen once the weather gets a little bit colder and conditions for transmitting influenza become more optimal."

Each strain of flu has different characteristics, and targets different groups of the population. The 1918 virus killed more healthy young adults than most influenzas - nearly half the victims were between the ages of 20 and 40.

This phenomenon shows some signs of repeating itself - older people, who are traditional victims of the flu, have fared better with this H1N1 strain, possibly because they've acquired a degree of immunity over the years.

"There is some evidence that this virus is attacking young, healthy adults at higher rates than other populations," Dr. Pekosz states. "Certainly there is more severe disease in children and in pregnant women. So there are segments of the population that should probably be extra vigilant come influenza virus season."

The Northern Hemisphere should be prepared for a flu season that is harsher than normal, Pekosz and other researchers are warning.

More people are likely to be infected, and there will therefore be a proportionately larger number of severe cases and deaths from H1N1 flu virus.

But health officials are urging people not to panic. The one thing this flu season has that the outbreak in 1918 lacked is vaccines. They urge people to take advantage of whatever vaccines and anti-virals are available this fall, as well as normal precautions and public health measures.