CDC issues antiviral recommendations for H7N9 influenza

The Centers for Disease Control and Prevention last week issued recommendations on antiviral treatment for avian influenza A(H7N9).

The recommendations apply to confirmed and probable cases of H7N9 infection and to cases under investigation. The CDC noted that the recommendations are based on currently available information, as well as the current lack of a vaccine for this virus, the severity of H7N9 disease, and the fact that current human-to-human virus transmission is limited but could increase in the future. The CDC said that clinicians should consider H7N9 influenza in patients with acute febrile respiratory illness who have “an appropriate recent travel or exposure history.”

The CDC recommended that all confirmed cases, probable cases, and H7N9 cases under investigation should receive antiviral treatment with a neuraminidase inhibitor as early as possible, even if it is more than 48 hours after onset of illness. In addition, it said, laboratory testing and initiation of antiviral treatment should occur simultaneously, and treatment shouldn't be delayed for laboratory confirmation of influenza or H7N9 infection.

The CDC also directed clinicians to consult its “Antiviral Drugs: Dosage” document for additional guidance, including dosage recommendations by age group. The CDC said oseltamivir is recommended for treatment of persons of any age, while zanamivir is recommended for children age 7 and older.

All of the recommendations, including additional recommendations for uncomplicated illness in outpatients and for hospitalized patients, are available online.

In a separate study, published early online April 24 by the New England Journal of Medicine, researchers examined data from 82 patients with H7N9 infection in China and found no epidemiologic relation in most cases. The median patient age was 63 years (range, 2 to 89 years), 73% of patients were male, and 84% lived in urban areas.

Approximately three-quarters of the 77 patients for whom data were available had been exposed to live animals, especially chickens. Seventeen patients (21%) died, with a median illness duration of 11 days. The researchers also examined 1,689 close contacts of case-patients, of whom 1,251 completed a seven-day monitoring period. Among these close contacts, 19 (1.5%) developed respiratory symptoms but none tested positive for the H7N9 virus.

The researchers could not rule out human-to-human transmission because H7N9 cases were found in two family clusters. However, they said that their results “suggest that the risk of secondary H7N9 virus transmission, including to health care personnel, is low at this time.”