Posted on 13 Nov 2009
Swine flu has infected 22 million people in the U.S. and killed 3,900 in the first six months of the pandemic, according to revised estimates of the influenza from the Centers for Disease Control and Prevention.
The death total is about a fourfold increase from previous tallies and the first specific estimate of total swine flu infections. U.S. health authorities are seeking a more accurate model to analyze the effects of the pandemic flu, also known as H1N1, Anne Schuchat, director of the Atlanta-based CDC’s Center for Immunization and Respiratory Diseases, said today.
Swine flu, first reported in April, is spreading at unprecedented rates for this time of year, Schuchat said. The disease puts young people, pregnant women and those with health conditions such as asthma and diabetes at greatest risk, with about 90 percent of the deaths of people younger than 64. Supply of the vaccine to prevent the disease has fallen far short of heath authorities estimates.
The previous reporting system was “potentially giving an incomplete story of the pandemic,” Schuchat said in a conference call with reporters. “What we’re really trying to do is give a bigger picture.”
The toll published by the CDC before today was based on confirmed cases in 10 states, while the new numbers extrapolate nationwide tallies from the same surveillance system. The estimates will be updated every three to four weeks and don’t include infections since Oct. 17, when swine flu has circulated at its highest rate, Schuchat said.
“We don’t think things have changed from last week to this week,” Schuchat said of the disease.
Swine flu has killed an estimated 540 children and teenagers younger than 18, CDC said today. The agency said Nov. 6 that the death toll for children was 129.
An estimated 98,000 people have been hospitalized so far, about half the number for a typical seasonal flu. However, the current rate of H1N1 infection, responsible for almost 8 percent of all doctors’ visits in the U.S., is the highest it has been at this time of year in 40 years of reporting, Schuchat said. Seasonal flu typically increases in winter months and peaks in February, according to CDC data.
“We’ve been tracking influenza for decades,” Schuchat said. “What we are seeing in 2009 is unprecedented.”
About 36,000 people die each year from seasonal flu, though the CDC doesn’t have exact numbers and relies on statistical models for its estimate. States aren’t required to report flu cases or deaths of adults, and influenza is rarely listed on death certificates of people who die from complications, making mortality difficult to track.
The previous H1N1 estimates were based on laboratory-confirmed cases, and most flu patients are never tested. About 222 people are infected for every person who has been hospitalized, according to the CDC’s model to estimate nationwide infections.
Vaccinations have been delayed by slower-than-expected manufacturing and shipping complications, Schuchat said today. About 41.6 million doses are currently available to states for distribution to local hospitals, clinics and physicians, less than half the amount CDC estimated July 29 would be ready by now.
The vaccine doses available are aimed at children and those younger than 25, pregnant women, caregivers of infants, health- care workers, and adults with chronic conditions that put them at risk for complications. Healthy adults, including the elderly, should wait until additional supplies arrive, the CDC has said.