Influenza Virus

Management of Influenza

In accordance with the CDC's Advisory Committee on Immunization Practices, the first option for reducing the effect of influenza is through annual vaccination with either inactivated (i.e., killed virus) vaccine or live attenuated influenza vaccine (LAIV). Both types of vaccine differ based on their route of administration, administration guidelines, virus strains and approved age and risk groups.3

Vaccination is the First Line of Defense Against Influenza

The CDC recommends annual vaccination for all people age 6 months and older.13

Limitations of Vaccines

  • Vaccine effectiveness can vary, since new strains of the influenza virus surface regularly. Therefore, influenza should not be ruled out in the differential diagnosis.
    • 17-59 years of age*: 70% to 90% effective
    • 50-64 years of age*: 52% effective
    • 58-104 years of age†: 17% to 53% effective

* Vaccine efficacy based on measurement of immune response.
† Vaccine efficacy based on measurement of antibody response.

The CDC Recommends Use of Neuraminidase Inhibitors for the Treatment and Prevention of Flu During the 2009-2010 Influenza Season14

  • Vaccination is the first line of defense against influenza. According to the CDC, antiviral medications can also be effective at treating and preventing influenza 14
  • The CDC recommends the use of oseltamivir (TAMIFLU) or zanamivir if an antiviral medication is used for the treatment or prevention of influenza 14
  • For the latest CDC recommendations, visit the CDC website

TAMIFLU Resistance Profile

  • Influenza viruses change over time. Emergence of resistance mutations could decrease drug effectiveness. Other factors (for example, changes in viral virulence) might also diminish clinical benefit of antiviral drugs. Prescribers should consider available information on influenza drug susceptibility patterns and treatment effects when deciding whether to use TAMIFLU. Refer to the CDC website for the most current information.
  • Study results in 1999 showed a 1.3% (4/301) level of resistance to TAMIFLU for adults and 8.6% (9/105) in pediatric patients aged 1 to 12 years 1
  • In a study of TAMIFLU postexposure prophylaxis in immunocompetent subjects conducted in 277 households, no TAMIFLU-resistant variants were detected in treated index cases or contacts 8
  • Please see Important Safety Information

Learn about TAMIFLU for influenza treatment and influenza prevention.

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Important Safety Information

Indications

TAMIFLU is indicated for the treatment of uncomplicated influenza caused by viruses types A and B in patients 1 year and older who have been symptomatic for no more than 2 days.

TAMIFLU is also indicated for the prophylaxis of influenza in patients 1 year and older.

Efficacy of TAMIFLU in patients who begin treatment after 48 hours of symptoms has not been established.

TAMIFLU is not a substitute for early and annual vaccination as recommended by the Centers for Disease Control's Advisory Committee on Immunization Practices (ACIP).

There is no evidence for efficacy of TAMIFLU in any illness caused by agents other than influenza viruses Types A and B.

Influenza viruses change over time. Emergence of resistance mutations could decrease drug effectiveness. Other factors (for example, changes in viral virulence) might also diminish clinical benefits of antiviral drugs. Prescribers should consider available information on influenza drug susceptibility patterns and treatment effects when deciding whether to use TAMIFLU.

Safety Information

TAMIFLU is contraindicated in patients who have had severe allergic reactions such as anaphylaxis or serious skin reactions such as toxic epidermal necrolysis, Stevens-Johnson syndrome, or erythema multiforme to any component of TAMIFLU.

In postmarketing experience, rare cases of anaphylaxis and serious skin reactions, including toxic epidermal necrolysis, Stevens-Johnson syndrome and erythema multiforme, have been reported with TAMIFLU. Tamiflu should be stopped and appropriate treatment instituted if an allergic-like reaction occurs or is suspected.

Influenza can be associated with a variety of neurologic and behavioral symptoms, which can include events such as hallucinations, delirium and abnormal behavior, in some cases resulting in fatal outcomes. These events may occur in the setting of encephalitis or encephalopathy but can occur without obvious severe disease. There have been postmarketing reports (mostly from Japan) of delirium and abnormal behavior leading to injury, and in some cases resulting in fatal outcomes, in patients with influenza who were receiving TAMIFLU. Because these events were reported voluntarily during clinical practice, estimates of frequency cannot be made but they appear to be uncommon based on TAMIFLU usage data. These events were reported primarily among pediatric patients and often had an abrupt onset and rapid resolution. The contribution of TAMIFLU to these events has not been established. Patients with influenza should be closely monitored for signs of abnormal behavior. If neuropsychiatric symptoms occur, the risks and benefits of continuing treatment should be evaluated for each patient.

Serious bacterial infections may begin with influenza-like symptoms or may co-exist with or occur as complications during the course of influenza. TAMIFLU has not been shown to prevent such complications.

Treatment efficacy in subjects with chronic cardiac and/or respiratory disease has not been established. No difference in the incidence of complications was observed between the treatment and placebo groups in this population.

No information is available regarding treatment of influenza in patients at imminent risk of requiring hospitalization.

Efficacy of TAMIFLU has not been established in immunocompromised patients.

The concurrent use of TAMIFLU with live attenuated influenza vaccine (LAIV) intranasal has not been evaluated. However, because of the potential for interference between these products, LAIV should not be administered within 2 weeks before or 48 hours after administration of TAMIFLU, unless medically indicated.

Adverse events that occurred more frequently in patients treated with TAMIFLU than in patients taking placebo and occurred in ≥2% of patients were (TAMIFLU%, placebo%):

  • Treatment in adults – nausea (10%, 6%), vomiting (9%, 3%), bronchitis (2%, 2%)
  • Treatment in pediatrics – vomiting (15%, 9%), abdominal pain (5%, 4%), epistaxis (3%, 3%), ear disorder (2%, 1%)
  • Prophylaxis of adults – headache (18%, 18%), nausea (7%, 3%), diarrhea (3%, 2%), vomiting (2%, 1%), abdominal pain (2%, 1%)
  • Prophylaxis of pediatrics – vomiting (10%, 2%), abdominal pain (3%, 0%), nausea (4%, 1%)
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