Many people who have died from swine flu in the United States were also infected with other bacteria, including one which can cause pneumonia or meningitis, US health officials said Wednesday.
Scientists who analyzed the cases of 77 patients who had the new strain of H1N1 flu and died found evidence of bacterial co-infection in around a third of the cases.
Of the 22 patients found to have a bacterial co-infection, nearly half had Streptococcus pneumoniae, a common bacteria which can cause pneumonia and "likely contributed to their death," the Centers for Disease Control and Prevention said in its weekly Morbidity and Mortality report.
Seven of the patients had Staphylococcus aureus, and one had haemophilus influenzae, which can also cause pneumonia.
The rest showed a variety of co-infections.
The patients ranged in age from two months to 56 years, with a median age of 31 years.
CDC epidemiologist Matthew Moore recommended that, in the light of the findings, "those at high risk for the serious complications from influenza check with their provider when they get their influenza vaccine about being vaccinated against pneumococcus."
The CDC recommends in any case that children under the age of five, "all persons between the age of two and 64 with high-risk conditions" and senior citizens older than 65 be vaccinated against Streptococcus pneumonia, but says only a small proportion of patients actually get the shots.
No data were available on the vaccination status of the 22 patients who had H1N1 flu and a bacterial co-infection, the CDC said, but one patient was younger than five-years-old and 15 others "had underlying medical conditions" that were indications for pneumococcal vaccine.