Bacterial lung infections were common among 77 people who died because of the 2009 H1N1 flu, a finding similar to past pandemics, the CDC said.
In a subset of the 600 U.S. deaths associated with the current pandemic, 29% had a bacterial coinfection, the agency said in a early release from the Morbidity and Mortality Weekly Report.
The most common pathogen found was Streptococcus pneumoniae, identified in 10 of the 22 cases of coinfection, the agency said. The finding underscores the need for vaccination against pneumococcus, according to CDC epidemiologist Matthew Moore, MD, one of the report’s co-authors.
“Our influenza season is off to a fast start, and, unfortunately, there will be more cases of bacterial infections in people suffering from influenza,” Moore said in a statement.
“It’s really important for people, especially those at high risk for the serious complications from influenza, to check with their provider when they get their influenza vaccine about being vaccinated against pneumococcus,” he said.
In previous pandemics, the agency said, most deaths blamed on the flu have occurred concurrently with a bacterial coinfection, but that had not been shown so far in the current outbreak.
Indeed, two early reviews of severe cases had shown no bacterial coinfections among 40 H1N1 inpatients, 10 of whom were in intensive care.
“These reports might have led to a perception that bacterial coinfections are playing a limited role or no role in influenza deaths during the current pandemic,” the CDC said.
But the CDC said such an absence of evidence might simply reflect the difficulty of identifying pathogens.
Although the current report established that bacterial coinfection is playing a role, the results don’t give information about the rate of bacterial pneumonia among H1N1 patients, the agency said.