Order Antivirals Before Influenza Is Lab-Confirmed, CDC Says

January 09, 2015

To take the edge off a bad influenza season, clinicians should prescribe antivirals for hospitalized, severely ill, and high-risk patients with flu symptoms without waiting for lab confirmation of the virus, the Centers for Disease Control and Prevention (CDC) announced today.

"Antivirals are underutilized," said CDC Director Tom Frieden, MD, MPH, in a press briefing today. "Doctors aren't using them as recommended."

These drugs, he said, can reduce symptoms, shorten the duration of illness, and prevent serious complications. They pack the biggest therapeutic punch when prescribed within 48 hours of the onset of flu symptoms.

"If you get them early, they could keep you out of the hospital and they might even save your life," he said. And better late than never also applies to prescribing an antiviral, he added. "Its treatment benefit may be present even if given later."

The CDC has studied the underuse of antivirals, he said, and the causes appear to be manifold.

"Clinicians may not be aware of the CDC guidance," Dr Frieden said. "There may be a perception that the drugs don't work. Some doctors and other clinicians are waiting for a positive test before prescribing medications or may not prescribe antivirals after a two-day window.

"These are areas where we're working to improve clinician awareness."

In a clinical advisory issued today, the CDC spelled out who exactly should receive antivirals for suspected influenza. In addition to hospitalized patients, and those with severe, complicated, or progressive illnesses, the list includes others at a higher risk for influenza complications because they are:

  • Aged younger than two years

  • Aged 65 years or older

  • People with chronic pulmonary, cardiovascular (except hypertension alone), renal, hepatic, hematological, and metabolic disorders (including diabetes), or neurologic and neurodevelopment conditions such as cerebral palsy

  • Immunosuppressed

  • Pregnant or postpartum women

  • Aged younger than 19 years and receiving long-term aspirin therapy

  • American Indians and Alaska Natives

  • Morbidly obese

  • Residents of nursing homes and other chronic-care facilities

The CDC recommends three antivirals for influenza — oseltamivir (Tamiflu, Roche Group), zanamivir (Relenza, GlaxoSmithKline), and peramivir (Rapivab, BioCryst Pharmaceuticals), approved last month. All three are neuraminidase inhibitors. The CDC does not recommend two other FDA-approved antivirals in the adamantane class called amantadine and rimantadine because influenza A viruses have become highly resistant to them. In addition, they do not work against influenza B viruses.

The nation has a sufficient supply of antiviral drugs, although spot shortages have cropped up, said Dr Frieden. "You may need to call around" different pharmacies.

A reporter asked Dr Frieden whether his agency's advice to prescribe antivirals like oseltamivir for flu-like symptoms before lab confirmation conflicted with its admonitions to prescribe antibiotics only when they are clearly needed, so as to reduce antibiotic resistance. "We have not seen the widespread emergence of resistance to Tamiflu," he replied. "The risk is of progressive illness, hospitalization, and death. The risk here is not of widespread emergence of resistance at this point."

Flu Hospitalizations Up Sharply for Seniors

Dr Frieden said prescribing antivirals was all the more important in what "is shaping up to be a bad year for flu." The reason is the predominance of the influenza A(H3N2) virus, which is nastier than the others. Making matters worse is that two-thirds of the A(H3N2) viruses in circulation have genetically mutated, or drifted, from the A(H3N2) strain used in the seasonal vaccine, rendering it less effective, although not entirely useless, said Dr Friedman.

The flu season, normally 13 weeks long, is about half way over, he said, noting that it is too early to say whether it has peaked.

According to the agency's latest Flu View summary, influenza activity was widespread in 46 states in the week ending January 3 compared with 43 states the week before. The percentage of outpatient visits for influenza-like illness stood at 5.6%, down a tad from 5.9%. However, the cumulative rate of influenza-related hospitalization for Americans aged 65 years or older during the current season almost doubled in a week's time, rising from 52 per 100,000 to 92. The CDC received reports of five more children dying of influenza in the week ending January 3, bringing the total for the current flu season to 26.


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