Tests Show More Swine Flu Immunity in Older Folks

ATLANTA -- New test results show what scientists have suspected -- people in their 60's and older have signs of greater immunity to the new swine flu virus.

Scientists think it's because older people have been exposed to other viruses in the past that are more similar to swine flu than more recent seasonal flus.

But the results come from complicated lab work and calculations, and it's not yet clear how safe older people actually are from the new infection, federal officials said.

"We can't say," said Dr. Anne Schuchat of the U.S. Centers for Disease Control and Prevention. So older people are advised to take the same precautions as their children and grandchildren.

In the new analysis, CDC scientists mixed the new swine flu virus with blood samples taken in the past from people in the United States and Europe to check for antibodies that would guard against infection. The samples were taken from healthy people before the new flu surfaced.

Significant protection was seen in one in three of the samples from people 60 and older, but in less than one in 10 of samples from younger adults. CDC officials said those results likely could be applied to Europe and the U.S., but they need to do more testing to find out if this would hold true in Mexico.

The number of samples was small, and the lab test hasn't been verified, so cautious CDC scientists weren't willing to say it shows a clear-cut immunity in older people.