The Hopkins team analyzed data from 140 pediatric patients diagnosed with H1N1 between June 2009 and August 2009, of whom 13 went on to develop critical illness and were admitted to the pediatric intensive care unit (PICU) at Hopkins Children's. The novel flu strain, originally called swine flu, emerged for the first time in April 2009.

Other findings reported in the article include:

Asthma was the most common underlying chronic condition (11 of the 13 children had it), followed by neuromuscular diseases like cerebral palsy.

Nearly half of the children became so sick they needed a ventilator to help them breathe. However, no children died or required ECMO (extra-corporeal membrane oxygenation), a last-resort critical-care device that takes over the patient's lungs and heart to oxygenate and circulate the blood when the patient's organs can no longer do so.

One-fourth of the children developed dangerous secondary bacterial infections, more often than previously believed, which points to the need for watchful monitoring for such infections in children with H1N1.

Source: Johns Hopkins Medical Institutions