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Young Kids Shed H1N1 Virus Longer

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  • Young Kids Shed H1N1 Virus Longer

    Children younger than 13 shed the pandemic H1N1 influenza virus over a longer period of time than older children and adults, a Taiwanese study showed.

    Although the median duration of viral shedding was nine days, it was significantly longer in younger children (11 days versus seven, P<0.001), according to Kuender Yang, MD, PhD, of Chang Gung Memorial Hospital-Kaohsiung Medical Center in Taiwan, and colleagues.

    "Why children have a longer period of viral shedding is unknown," the researchers wrote in the August issue of Emerging Infectious Diseases. "Delayed cell-mediated immunity in children responding to a novel virus may explain, in part, their longer viral shedding time."

    The researchers also found that patients who developed pneumonia had significantly higher viral loads than those with upper respiratory tract infections (P<0.001) or bronchitis (P=0.002).

    Taken together, the researchers wrote, "these results suggest that younger children may require a longer isolation period and that patients with pneumonia may require treatment that is more aggressive than standard therapy for pandemic (H1N1) 2009 virus."

    Yang and colleagues tested 1,052 patients treated at their center for the presence of influenza using real-time reverse-transcription polymerase chain reaction; 602 were infected with the pandemic strain.

    Of those with confirmed H1N1, 86.4% went to the hospital within two days of the onset of fever. All received oseltamivir (Tamiflu) for five days.

    Overall, 3.4% had severe illness, including pneumonia and meningoencephalitis. There were no deaths.

    In patients with confirmed infection with the pandemic strain, viral load was inversely correlated with the number of days after the onset of fever (P<0.001). Viral load was high for the first three days.

    The reason patients with pneumonia had higher viral loads than those with other respiratory infections "may be a reflection of disease severity or impaired host immunity, requiring immediate attention and aggressive treatment," according to Yang and his colleagues.

    The median duration of viral shedding (nine days) was longer than that seen in previous studies.

    The researchers noted that that could be because of the younger age of this study population (median age 10.1) compared with other studies. Age was the only independent predictor of the duration of viral shedding.

    Nearly nine out of every 10 children younger than 13 had detectable viral RNA for at least a week, and 36% had detectable RNA for at least two weeks.

    They noted that "because all of our patients received oseltamivir treatment, we could not determine the actual effect of the antiviral therapy on infection caused by the novel pandemic virus."