by Anthony Fiore, MD, MPH, medical epidemiologist for the Influenza Division of the CDC.


We still have a lot to learn about treatment of 2009 H1N1 influenza, but fortunately the antiviral drugs we use for treating seasonal influenza - oseltamivir (Tamiflu) or zanamivir (Relenza)- are safe and effective, and very few 2009 H1N1 influenza viruses have been resistant to these drugs. Listed below are some key facts that healthcare providers and patients should keep in mind when thinking about using antiviral medicines to treat influenza.

The earlier antiviral treatment is given, the more likely it will be effective.
We know from experience with seasonal influenza that beginning treatment within 48 hours can reduce how long illness lasts. For most healthy people, the worst symptoms of influenza will be in the first 3 days of illness, so it makes sense that starting antiviral medicines 3 or more days after the start of a typical influenza illness will be less likely to help.

Patients who are severely ill should get treated right away no matter when their illness started.
Patients with severe illness should receive antiviral treatment as soon as possible regardless of when symptoms started, because illness in these patients often runs a longer course. Severe illness means concerning symptoms such as difficulty breathing, symptoms improve but then return with fever and worse cough, pain or pressure in the chest or abdomen, or confusion. For patients with severe illness that requires hospital care, treatment makes a difference, and can reduce the risk for death. All hospitalized patients with suspected or confirmed 2009 H1N1 should receive antiviral treatment with a neuraminidase inhibitor antiviral drug - either oseltamivir or zanamivir - regardless of age, risk factors or how long its been since illness started.

Treatment shouldn't wait for laboratory test results to come back.
If your healthcare provider suspects you have influenza and thinks antiviral treatment is needed, then treatment should begin as soon as possible. Antiviral medications are safe and effective, and the potential benefits outweigh the small risk of side effects (which are typically minor and self limited) in any patient with risk factors for severe illness. Some rapid influenza screening tests may give false negative results and obtaining more accurate testing results can take more than a day.

You don't have to be hospitalized to get treated.
Outpatients who 1) have risk factors for more severe infection (see below for the risk factors), 2) have evidence of pneumonia, or, 3) appear to worsening or unstable, might also benefit from treatment regardless of when illness started. But as with any illness, earlier treatment is better. Healthcare providers should consider ways to reduce the time it takes for patients who need treatment to get it. Patients who are at higher risk for severe illness and who get what they think might be influenza should contact a healthcare provider as soon as possible. That's also true for any patient who takes a turn for the worse or who has high fever and other symptoms for more than a few days.

Decisions about treatment are always ultimately up to the clinician and the patient
Treating those who have severe illness or who are at higher risk for severe illness is the main goal of antiviral treatment recommendations. Treatment generally is not necessary for healthy older children and adults younger than 65 years old who don't have severe influenza. But there are potential benefits of treating healthy persons early in the course of their illness (within 48 hours of the start of symptoms), including the possibility of reducing the duration of cough or fever by a day or 2. Even healthy persons can get severe illness and early treatment might further reduce their already small risk of influenza complications. You and your healthcare provider have to weigh these potential benefits against the costs and availability of antiviral drugs and the small risk for drug side effects. Healthcare providers use their experience and judgment to give advice on treatment decisions like this all the time.

Even if you are getting antiviral treatment, you might still pass the virus to others
Patients receiving treatment can still infect others. Therefore, good hand washing and respiratory hygiene practices should continue during treatment to prevent transmitting illness to others. Information about home care of ill persons for providers and patients is available at Taking Care of a Sick Person in Your Home and Home Care Guidance:
Physician Directions to Patient/Parent.

Because many communities are now experiencing widespread flu activity, the use of influenza antiviral drugs in the United States has increased. Patients with severe influenza are getting treated more often and more quickly than at the start of the pandemic. It can be difficult to keep up with the recommendations for use of antivirals, because these have been revised several times as we have learned more about who is at higher risk for severe infection and who is most likely to need treatment. What we know so far is that certain persons are at higher risk for more severe illness:

• pregnant women and women who have given birth within the previous two weeks


• infants and children younger than 2 years old


• adults 65 years old or older


• any child or adult with with a chronic medical condition, like diabetes, heart disease, or asthma.

Several studies have also shown that persons who are very obese (body-mass index greater than or equal to 40), and possibly also persons who are obese (body-mass index greater than or equal to 30) are at higher risk for severe influenza - perhaps because many have other underlying medical conditions, or because obese persons just tend to have more complications from any illness compared to persons who are less heavy.

For more information please see the latest CDC antiviral guidance: Treatment (Antiviral Drugs)

Labels: antivirals, CDC, H1N1, symptoms