Also, flu pandemics tend to follow a pattern like the one taking place now. They come in "waves" and there are always additional "waves" in the second and third year after flu strain's initial appearance, he said.
"It just becomes one of the circulating viruses," Siegel said.
It's unlikely that another severe outbreak of H1N1 would occur in the United States, he said.
"We have developed a 'herd immunity' through previous exposure to the virus and vaccination, so it slows the spread," he said.
According to the CDC, one reason that children and young adults were more vulnerable to the H1N1 strain back in 2009 is that this strain hadn't circulated widely since the early half of the 20th century. As a result, CDC studies found that no children and very few adults younger than 60 had existing antibodies to the 2009 H1N1 flu virus. Curiously, about one-third of adults 60 and older are thought may have antibodies that may help protect against the virus.
To learn more about the H1N1 flu, visit the U.S. Centers for Disease Control and Prevention.
SOURCES: Tom Skinner, spokesman, U.S. Centers for Disease Control and Prevention, Atlanta; Marc Siegel, M.D., associate professor, medicine, New York University, New York City; Feb. 8, 2012, Associated Press
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