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

(ChinaPost.com.tw) – Adults older than 52 may have been exposed to a virus that gives some protection against A(H1N1) flu, explaining why younger people account for the largest percentage of those hospitalized, a U.S. scientist said.

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.

Read more….