Influenza Symptoms & Clinical Overview | TAMIFLU� (oseltamivir phosphate)

Influenza Management

Clinical Overview of Influenza

In all patients, the flu can take its toll.

On average, influenza affects an estimated 5 to 20 percent (16-62 million) of the United States population annually.^2,36

The severity of influenza is unpredictable and often underestimated.

The annual range of deaths associated with seasonal influenza spans 3,000 to 49,000 (1976-2007).²⁶
A study of influenza type 2009 H1N1 revealed the mean age at death of laboratory-confirmed influenza was 37.²⁷

Flu is a major cause of hospitalization:²⁸

In 2004, the CDC reported that, on average, more than 200,000 people are hospitalized each year with influenza-related infections.
Annual incidence of hospitalizations ranged from 157,911 in 1990-1991 to 430,960 in 1997-1998.
The yearly rate of influenza-associated hospitalizations is increasing.
Treatment with Tamiflu has not been proven in pivotal trials to reduce the rate of mortality or hospitalization.

Symptoms of influenza

Influenza is spread from person to person through respiratory droplets that are dispersed when an infected person coughs or sneezes in close proximity to someone who is not infected.²

The typical incubation period for influenza is 1-4 days (average: 2 days).^2,18

Adults can be infectious from 1 day before onset of symptoms to 5-7 days after illness onset.²

Influenza is more infectious in children than adults.²⁹

Children can shed earlier, before illness begins, and for longer once illness starts.
Viral shedding can occur for up to 21 days (median 7-8 days) in children.

Uncomplicated influenza is characterized by abrupt onset of signs and symptoms that may include¹⁷:

Fever
Chills
Myalgia
Headache
Tiredness
Sore throat
Rhinitis
Chest discomfort, cough
Some people may have vomiting and diarrhea, though this is more common in children than adults.⁴
Most people who get influenza will recover in a few days to less than 2 weeks.⁴

Next Step: Learn about the impact of influenza ›

Did you know?

In a clinical study, Tamiflu prophylaxis reduced postexposure flu transmission in children aged 1-12 years by 82%.²³

Learn more ›

Indications and Limitations of Use

TAMIFLU is indicated for the treatment of acute, uncomplicated illness due to influenza infection in patients 2 weeks of age 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 and Prevention Advisory Committee on Immunization Practices.
There is no evidence for efficacy of TAMIFLU in any illness caused by agents other than influenza virus types A and B.
Influenza viruses change over time. Emergence of resistant 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.

Important Safety Information

Severe allergic reactions

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, and erythema multiforme to any component of TAMIFLU.
In postmarketing experience, 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.

Neurologic symptoms

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. Closely monitor patients with influenza for signs of abnormal behavior. If neuropsychiatric symptoms occur, evaluate the risks and benefits of continuing treatment for each patient.

Bacterial infections

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

Limitations of populations studied

Efficacy of TAMIFLU in the treatment of influenza in patients with chronic cardiac disease 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 with any medical condition sufficiently severe or unstable to be considered at imminent risk of requiring hospitalization.
Efficacy of TAMIFLU for treatment or prophylaxis of influenza has not been established in immunocompromised patients.
Safety and efficacy of TAMIFLU for treatment of influenza in pediatric patients less than 2 weeks of age have not been established.
Safety and efficacy of TAMIFLU for prophylaxis of influenza have not been established for pediatric patients less than 1 year of age.

Concurrent use with live attenuated influenza vaccine

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.

Most common adverse reactions

The safety profile observed in pediatric patients 2 weeks to less than 1 year of age was consistent with the established safety profile of pediatric subjects aged 1 year and above, with vomiting, diarrhea, and diaper rash being the most frequently reported adverse reactions.
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%).
- Treatment in pediatrics — vomiting (15%, 9%), abdominal pain (5%, 4%), ear disorder (2%, 1%).
- Prophylaxis of adults — 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%).

Please see the TAMIFLU full Prescribing Information for complete safety information.