As the World Health Organization raised its infectious disease alert level Wednesday and health officials confirmed the first death linked to swine flu inside U.S. borders, scientists studying the virus are coming to the consensus that this hybrid strain of influenza -- at least in its current form -- isn't shaping up to be as fatal as the strains that caused some previous pandemics.
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Scientists see this flu strain as relatively mild
Genetic data indicate this outbreak won't be as deadly as that of 1918, or even the average winter.
For The Record
Los Angeles Times Friday, May 01, 2009 Home Edition Main News Part A Page 4 National Desk 1 inches; 56 words Type of Material: Correction
Swine flu: An article in Thursday's Section A about the risks posed by swine flu said that in the United States annually "between 5% and 20% of the population becomes ill from the flu and 36,000 people die -- a mortality rate of between 0.24% and 0.96%." The correct mortality rate is between 0.06% and 0.24%.
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In fact, the current outbreak of the H1N1 virus, which emerged in San Diego and southern Mexico late last month, may not even do as much damage as the run-of-the-mill flu outbreaks that occur each winter without much fanfare.
"Let's not lose track of the fact that the normal seasonal influenza is a huge public health problem that kills tens of thousands of people in the U.S. alone and hundreds of thousands around the world," said Dr. Christopher Olsen, a molecular virologist who studies swine flu at the University of Wisconsin School of Veterinary Medicine in Madison.
His remarks Wednesday came the same day Texas authorities announced that a nearly 2-year-old boy with the virus had died in a Houston hospital Monday.
"Any time someone dies, it's heartbreaking for their families and friends," Olsen said. "But we do need to keep this in perspective."
Flu viruses are known to be notoriously unpredictable, and this strain could mutate at any point -- becoming either more benign or dangerously severe. But mounting preliminary evidence from genetics labs, epidemiology models and simple mathematics suggests that the worst-case scenarios are likely to be avoided in the current outbreak.
"This virus doesn't have anywhere near the capacity to kill like the 1918 virus," which claimed an estimated 50 million victims worldwide, said Richard Webby, a leading influenza virologist at St. Jude Children's Research Hospital in Memphis, Tenn.
When the current virus was first identified, the similarities between it and the 1918 flu seemed ominous.
Both arose in the spring at the tail end of the flu season. Both seemed to strike people who were young and healthy instead of the elderly and infants. Both were H1N1 strains, so called because they had the same types of two key proteins that are largely responsible for a virus' ability to infect and spread.
