May 22, 2009
There may be a reason that mostly children, teens and young adults are
being hit hardest by the outbreak of swine flu in the U.S. The Centers
for Disease Control and Prevention (CDC) says older folks appear better able to ward off
the virus.
"The study that CDC is reporting today in our Morbidity and Mortality Weekly Report suggests that older adults might have some pre-existing antibody against this new H1N1 strain, but we don't know yet what that will mean in terms of actual immunity or clinical protection," said Dr. Anne Schuchat, CDC's director of immunizations and respiratory diseases. "It's interesting that the laboratory findings we're reporting seem to correlate with the epidemiologic data that we have so far that suggests most of the illnesses we're seeing have occurred in younger people and have spared the elderly who are at great risk for seasonal influenza."
But otherwise, Schuchat said at Thursday's briefing with reporters, the swine flu, or H1N1 virus, is behaving similarly with the seasonal flu viruses.
"But it's new and we're still making sure we understand it going forward," she said.
Of the cases that have been reported to the CDC which have gone under some type of laboratory testing, 64 percent of those are occurring in people between five and 24 years of age. Only about one percent of the cases are in people over 65.
The CDC says the vast majority are in younger persons and the biggest proportion of those are people in the five to 24-year-old age group.
Because the seasonal flu is unpredictable and causes a lot of illnesses each year, the CDC suspects the H1N1 virus will also be unpredictable. Though the virus has now spread to 48 states, Schuchat said the CDC is seeing activity decline in some areas.
"But we're seeing increased or localized outbreaks in other areas and so we should expect to see more cases, more hospitalizations and potentially more deaths as we move into the weeks and months ahead," Schuchat said.
At the national level, Schuchat said the CDC is seeing the percent of visits for influenza-like illness is starting to turn down, something she called a good sign and consistent with the idea that the worst may be over.
On the other hand, in our New England region, we're still seeing an upsurge in influenza-like illness and in the New Jersey-New York area we're still seeing an upsurge, Schuchat said. "The Mid-Atlantic area is seeing a decline. The southeast area is somewhat seeing a decline, but it may be too soon to say about that and the Midwest and southwest are also starting to see declines."
