New data on hospitalizations and deaths caused by the pandemic H1N1 influenza virus show that it is "a disease of the young," said Dr. Anne Schuchat of the Centers for Disease Control and Prevention in a news conference this morning. From Sept. 1 to Oct. 10, there were 4,958 hospitalizations from laboratory-confirmed swine flu in the 27 states reporting to the CDC, said Schuchat, who is director of the agency's National Center for Immunization and Respiratory Diseases. More than half of those cases, 53%, were in people under age 25; 39% were in those age 26 to 64 and only 7% were in those age 65 and over. With seasonal flu, in contrast, 60% of hospitalizations are in patients 65 and over.
The disparity is even worse for fatalities. During the same time period, there were 292 deaths from swine flu in the 28 states reporting. In that group, 23.6% occurred in people under age 25, 65% in people 25 to 64 and only 11.6% in those 65 and over. "That is dramatically different from seasonal flu, in which 90% of the fatalities occur in those over 65," Schuchat said.
The difference, most researchers now suspect, is caused by the fact that the elderly have been exposed to a swine-related virus in the past and that has produced some residual immunity, so that they are less likely to be infected and are not as severely affected when they do contract it. Younger people have no such immunity.
Schuchat said CDC is emphasizing the use of antiviral drugs such as Tamiflu in people with severe illness who have underlying health conditions or who are pregnant. "If you suspect flu in these groups, give the antiviral," she said. "We don't want to wait for laboratory confirmation." She also noted that physicians should not be fooled by a negative finding on a rapid test for flu because they are relatively inaccurate. If a patient is sick, "don't believe a negative rapid test," she said.
As of Monday evening, there were 12.8 million doses of swine flu vaccine available, more than half of them the injectable form. About 10.8 million doses had been ordered by states.
-- Thomas H. Maugh II