Adults older than 52 may resist A(H1N1) flu, says U.S. CDC

The virus that caused the 1918 Spanish flu pandemic circulated until a bird flu virus replaced it in a 1957 world outbreak, Daniel Jernigan, deputy director of the Centers for Disease Control and Prevention influenza division, told reporters today. Exposure to the earlier virus "may allow you to have some protection" to swine flu, Jernigan said.

Swine flu, called H1N1, has sickened more than 10,000 people in 41 countries, according to the World Health Organization. Researchers have been trying to explain why more than 60 percent of U.S. cases have been among those aged 5 to 25, Jernigan said. Swine flu also lands people younger than 50 in the hospital more often than seasonal flu.

"It's one of the few good reasons to be over the age of 50," Robert Belshe, director of St. Louis University's vaccine center, said today in an interview. People born before 1957 were probably infected with a swine flu relative that left antibodies giving some natural immunity, he said.

The swift spread of swine flu in Japan has pushed WHO to consider declaring a pandemic, said Hitoshi Oshitani, former head of the agency's Western Pacific region. WHO has confirmed 80 deaths and the U.S. counts 5,710 cases. Utah today reported the ninth U.S. death.

Schools and Flu

U.S. health officials are still seeing "a significant number" of school-age children with swine flu "and increasing numbers in people 50 and over," Jernigan said.

Mitchell Weiner, a 55-year-old assistant principal at Intermediate School 238 in Queens, New York, died May 17. Jernigan said that those hospitalized for the illness were generally younger.

"When we look at the number of cases that have been hospitalized, the median age of those being hospitalized is 19 years," Jernigan said. "Those 19 to 49 are the largest chunk being hospitalized."

About 18 percent of those sick enough to need hospital care are ages 10 to 18 and another 11 percent are from 5 to 9 years old, Jernigan said. The U.S. has had at least 247 people hospitalized with swine flu, Jernigan said.

The 1918 Spanish flu killed an estimated 50 million people worldwide. The 1957 pandemic killed about 2 million. Seasonal flu epidemics cause about 250,000 to 500,000 deaths each year, according to WHO.

CDC Publication

The CDC will publish a report tomorrow elaborating on the immunity finding, Jernigan said. Studies published in the New England Journal of Medicine May 7 said that swine flu evolved from human viruses circulating in pigs for more than a decade and that older people may have some immunity because of exposure to similar germs.

Belshe, of St. Louis University, wrote a commentary published with the New England Journal of Medicine studies. His school receives funding from the National Institutes of Health to evaluate vaccines.

The swine flu virus also infected pigs in 1918, Belshe said. It's been circulating in animals since then, he said. The swine flu virus contains genetic elements of bird, pig and human influenzas.

"It's not 1918 again, it's 1918 continued," Belshe said.

Swine flu will continue spreading in the U.S. in the next few months, usually a season without much influenza, and may surge again after that, Jernigan said.

The virus spreads at about the same rate as seasonal flu, but "a larger percentage of the population may have no immunity" to it, Jernigan said.

Subscribe to The China Post and save 25%. Click here

SharePrintEmail

Write a Comment

Enter your comments - 3000 characters max

Type in image code

Submit

 Receive China Post promos Respond to this email