Many people who've died from swine flu also have been infected with pneumonia bacteria, underscoring the need for vaccination against that bug, too, federal health officials said Wednesday.
Of 77 people who died from complications of the H1N1 strain between May 1 and Aug. 20, 22, or nearly 30 percent, also had bacterial co-infections, including some caused by pneumococcus, according to a Centers for Disease Control and Prevention report.
Seven of the victims were children aged 15 and younger, the report showed.
Those infections likely worsened the illness and contributed to the deaths, six of which occurred in previously healthy people with no known medical conditions, the data showed. CDC officials urged people at high risk for flu complications to check with doctors about getting a pneumonia vaccine in addition to the recommended seasonal and H1N1 flu shots.
"It's those bad pneumonia infections that are the complicating factor," said Dr. William Schaffner, an infectious disease expert and director of preventive medicine at Vanderbilt University.
Bacterial infections key in 1918 pandemic
Influenza can cause viral pneumonia, but it can also weaken the system enough to allow opportunistic bacteria to surge, resulting in separate, potentially deadly infections, said Dr. Gregory Poland, a infectious disease expert at the Mayo Clinic.
Such bacterial co-infections are now believed to have contributed to many, if not most, of the more than 50 million deaths worldwide during the 1918 influenza pandemic, although medical historians continue to debate the question.
Most children under 5 receive pneumonia vaccinations as part of routine care, but many older children and adults miss the recommended shots, said Schaffner, who urged doctors to be vigilant about vaccinating their patients.
Video: How to create a swine flu emergency kit CDC reports that 936 people died and more than 10,000 were hospitalized with flu and pneumonia between Aug. 30 and Sept. 19, with nearly all flu cases attributed to H1N1 infections.
In the latest report, scientists analyzed tissue samples collected from swine flu victims in eight states. Patients who died ranged in age from 2 months to 56 years, with a median age of 31. Some of them may have been eligible for the pneumonia vaccine.
"Our influenza season is off to a fast start and unfortunately there will be more cases of bacterial infections in people suffering from influenza," said Dr. Matthew Moore, a CDC epidemiologist.
All children under 5 should receive the pneumococcal conjugate vaccine and people at high risk of pnemonia between the ages of 2 and 64 and those older than 65 should receive another pneumonia vaccine known as PPSV23, CDC officials said.
Overall, most cases of swine flu remain mild, but patients and health officials must remain alert for serious complications, the CDC's director told NBC news.
“This is uncharted territory for an influenza season,” Dr. Thomas Frieden said. “We’ve had already many millions of cases and will have many millions of cases more.”
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