Simultaneous infection of the H1N1 influenza and methicillin-resistant Staphylococcus aureus (MRSA) increased the risk for flu-related mortality 8-fold among previously healthy children during the 2009 H1N1 pandemic, according to research led by Children's Hospital Boston.
With emergency funding from the National Institutes of Health, study leader Adrienne Randolph, MD, MsC, of the Division of Critical Care Medicine at Children's Hospital Boston, and her colleagues in the Pediatric Acute Lung Injury and Sepsis Investigator's Network tracked 838 children admitted to 35 pediatric ICUs around the country with probable 2009 H1N1 influenza from April 2009 to April 2010.
The median age of the critically-ill children was 6 years. Most had respiratory failure, two-thirds required mechanical ventilation, and some required extracorporeal membrane oxygenation (ECMO) for advanced cardiac and respiratory support. Their disease progressed rapidly, and 75 children (9 percent) died, two-thirds of them within two weeks of ICU admission.
"Some children were quickly overwhelmed, and many died despite centers doing everything to save them," Randolph said, according to a press release. "Early in the pandemic, centers were worried that they would run out of ventilators, that they would run out of ICU beds."
While most of the critically-ill children had one or more chronic health conditions that increased their risk, such as asthma, neurologic disorders or compromised immune systems, 251 children (30 percent) were previously healthy. Among the healthy children, the only risk factor that was identified for death from influenza was a presumed diagnosis of MRSA co-infection in the lung.
"There's more risk for MRSA to become invasive in the presence of flu or other viruses," says Randolph, according to the press release. "These deaths in co-infected children are a warning sign."
Although many of the MRSA co-infected children received vancomycin promptly at or before ICU admission, a large number of them died anyway. According to the press release, the researchers say they don’t know why the antibiotic didn’t save those children, but they hope the recent findings will promote flu vaccination among all children aged 6 months and older. No flu vaccine is currently available for children younger than 6 months.
"The 2009 H1N1 virus has not changed significantly to date," notes Tim Uyeki, M.D., MPH, of the Influenza Division of the National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention (CDC), a senior investigator on the study, according to the press release. "Infections of children in the U.S. with 2009 H1N1 virus are expected this season and need to be prevented and treated appropriately. Influenza vaccination protects against 2009 H1N1 illness."
This study was published November 7 by the journal Pediatrics
