Washington - The nation's top immunization expert Tuesday warned physicians to treat suspected cases of swine flu immediately rather than waiting for the results of a common but "unreliable" rapid test. Dr Anne Schuchat, director of the National Centre for Immunization and Respiratory Diseases, also confirmed that children and youth under age 25 are the highest risk group for H1N1 influenza infection.
The pattern of swine flu infection - 53 per cent of the 4,958 US hospitalizations recorded since early September were of patients under age 25 - reverses the pattern of ordinary flu, which normally hits those over 65 hardest, she said.
Schuchat also sought to calm increasing public worry that there is not enough H1N1 vaccine to go around.
Shortages have occurred not only of the H1N1 flu vaccine but also of regular seasonal flu vaccine in the face of increased public demand.
"We wish we had more vaccine and that more of it had been given by now," she said.
Schuchat announced an update in the Centers for Disease Control and Prevention's guidelines for physicians about the urgency of immediately treating "severely ill" patients with antivirals such as Tamiflu.
"We want to stress how important early treatment with antiviral is," Schuchat told reporters. "We don't want doctors to wait until the last moment for confirmation of the disease."
She said rapid tests for the H1N1 flu were "unreliable" and doctor's should not "believe a negative rapid test result."
From September 1 to October 10, reports from 28 US states confirmed 292 deaths from swine flu, including 24 per cent under age 25; 65 per cent in the age 25-65 age group; and 11 per cent in the over-65 group. Because the information was not from all 50 states, she indicated that actual deaths were likely higher.
During normal seasonal flu, 90 per cent of all deaths are among those age 65 and older.
"It's almost completely reversed here," Schuchat said.
More than 4,000 people around the world have died from swine flu, which originated in Mexico in April and quickly spread to the United States.
Schuchat called for "patience" from the US public over the lagging supply of both H1N1 and seasonal flu vaccines.
The drug industry has produced 12.8 million doses of swine flu vaccine, with 10.8 million of them already accounted for by orders.
For regular seasonal flu prevention, 82 million doses have already been distributed and another 32 million doses are expected to be available through November, Schuchat said.
"We have seen excellent response to early availability ... It looks like the American public is stepping up to get it," she said.
She predicted a "very long" swine flu season, with a recurrence in the spring, similar to the pattern of the 1957 Asian flu. First priority for vaccine goes to the under-25 age group; second priority goes to those in the 25-65 group who are pregnant, suffer asthma, diabetes or other serious chronic problems, or who work in the health care field or with young children.
There has been growing US public debate about the safety of the swine flu vaccine and the rapidity of its development, with many parents deciding against immunization for their children.
"Not being vaccinated and not having your children vaccinated does put them at risk," Schuchat said. "Hospitalizations and death continue, and occur in younger people than we see in seasonal flu. Each case is tragic for the family."
The vaccine expert also urged immunizations against pneumonia, the most common complication of severe H1N1 cases and a frequent cause of death, along with secondary bacterial infections.
Schuchat said the pneumonia vaccine was widely available since there had been a "low uptake" in demand for it this year.
On Friday, the World Health Organization (WHO) warned about the increased incidence of viral pneumonia among swine flu victims and the added strain it could place on hospital emergency rooms and intensive care units.
More than half - 55 per cent - of US patients hospitalized for swine flu had underlying medical conditions, the US Centres for Disease Control said recently.
On Monday, US agricultural officials said the department had detected the first case of this swine flu variant in pigs in the US. Swine flu has badly affected pork producers in the United States and Mexico, though the virus is actually a mix of strains from pigs, humans and avian influenza.
