Treat H1N1 Influenza Like Seasonal Flu, CDC Says

Kate Traynor

BETHESDA, MD 07 May 2009—People with uncomplicated febrile illness caused by the recently detected H1N1 influenza virus generally do not need antiviral treatment unless they are at high risk for flu-related complications, according to a revised interim guidance document released last night by the Centers for Disease Control and Prevention (CDC).

CDC now recommends antiviral therapy with zanamivir or oseltamivir for the treatment of people who have been hospitalized with "confirmed, probable or suspected novel influenza (H1N1)" infection.

Also recommended to receive treatment are H1N1-infected people in the same populations that are considered to be at high risk for complications from seasonal influenza virus infection. This group includes children under age 5 years, adults 65 years or older, pregnant women, nursing home residents, and people with diabetes, asthma, sickle cell disease, or other chronic conditions.

Before last evening, CDC had recommended antiviral therapy beginning as soon as possible after symptom onset in anyone ill from influenza known or suspected to be caused by the novel H1N1 strain.

"The clinical treatment guidance now is much more in line with what we took with seasonal flu," CDC Acting Director Richard Besser said today. "The reason for that is that we have additional information in terms of severity. And our feeling, from the severity, is that this strain is currently acting much more like a seasonal flu strain."

As of 11:00 this morning, CDC had confirmed 896 cases of H1N1 infection in 43 states. A total of 42 U.S. hospitalizations have been attributed to the virus, and two virus-related deaths have been confirmed in this country. Besser reiterated that he expects the case numbers to grow as the virus moves through communities.

Besser said CDC is involved in several studies of the virus, including whether the use of antiviral medications has an effect on viral shedding and how the virus is transmitted in health care settings.

He said health care setting work is taking place in the United States and Mexico, where the virus has been most active.

"The goal here is to make sure that we're providing the best guidance possible for health care workers," Besser said.

Although the new H1N1 virus has caused mostly mild disease in the United States, CDC remains concerned about the possibility that pathogen could evolve into a deadly strain in the future.

"We'll be following this very closely in the Southern Hemisphere," which is about to enter its influenza season, Besser said. "That will give us clues to what we might see in the fall."