Who should get Tamiflu for H1N1 flu?

If this past weekend is any indication of phone calls to come, I will be busy fielding requests for Tamiflu for suspected 2009 A(H1N1) which is what we're calling swine flu these days. Patients are understandably nervous for themselves and their families with regards to the spread and severity of influenza illness.

There are 2 available antivirals which are active against 2009 A(H1N1)-- oral Tamiflu (oseltamivir) and inhaled Relenza (zanamivir). For some reason, I've always reached for Tamiflu, and a brief search for a comparison of one antiviral to the other suggests that I am just another victim of an effective marketing campaign by Roche Pharmaceuticals. Nevertheless, be it Tamiflu or Relenza, one of the biggest fears per flu-ologists is that the novel H1N1 flu will become resistant to these worthy drugs, and they will be rendered powerless against the bug.

So what does the CDC have to say on the subject? They along with the WHO (the World Health Organization, that is, not the '60's band) recommend that antiviral treatment be undertaken in accord with the following guidelines:

1. Treatment is recommended for all hospitalized patients with confirmed, probable or suspected 2009 H1N1 or seasonal influenza.
2. Treatment generally is recommended for patients who are at higher risk for influenza-related complications.
3. Treatment should be initiated empirically when the decision is made to treat patients who have illnesses that are clinically compatible with influenza. Treatment should not await laboratory confirmation because laboratory testing can sometimes delay treatment and because a negative rapid test does not rule out influenza.(1)

In other words, if the patient is sick enough to be hospitalized with flu-like illness, initiate treatment immediately. While these antivirals work best if initiated in the first 48 hours of illness, evidence suggests that hospitalized patients with seasonal flu fare better with respect to risk of death and length of hospitalization if Tamiflu therapy is started even if it's more than 48 hours after onset. Those known to be at higher risk of flu-related complications include pregnant women, persons who are immunocompromised (undergoing say chemotherapy or treatment for rheumatoid arthritis), or those with underlying medical illnesses such as diabetes, asthma, or heart disease. And finally, if we providers determine that a patient meets one of these criterion, get 'em going on it and don't wait for final proof!

These recommendations highlight the urgency with which certain subgroups of flu victims should be treated. The CDC, therefore, goes on to make further suggestions as to handle the upcoming flu season and the avalanche of requests for antiviral medications. These include:

1. Provide information for patients at higher risk for influenza complications about signs and symptoms of influenza and need for early treatment after symptom onset.
   
2. Ensure rapid access to telephone consultation and clinical evaluation for these patients as well as patients who report severe illness.
3. Consider empiric treatment of patients at higher risk for influenza complications based on telephone contact... if this will substantially reduce delay before treatment is initiated. In selected circumstances, providers may consider giving a prescription for an influenza antiviral to selected patients who are higher risk for influenza complications.
4. Request that patients at higher risk for influenza complications contact the provider if signs or symptoms of influenza develop, obtain the medication as quickly as possible and initiate treatment.
   
5. Counsel patients about influenza antiviral benefits and adverse effects, the potential for continued susceptibility to influenza virus infection after treatment is completed (because of other circulating influenza viruses or if illness was due to another cause).(2)

What about antiviral chemoprophylaxis wherein antivirals are given to at-risk persons exposed to someone who is fluish? Please note in no case do these recommendations include giving Tamiflu to any old person traveling and worried regarding flu exposure except as outlined in the 3rd guideline above.

1. Persons who are at higher risk for complications of influenza and are a close contact of a person with confirmed, probable, or suspected 2009 H1N1 or seasonal influenza during that person’s infectious period.
2. Health care personnel, public health workers, or first responders who have had a recognized, unprotected close contact exposure to a person with confirmed, probable, or suspected 2009 H1N1 or seasonal influenza during that person’s infectious period.
3. Antiviral agents should not be used for post exposure chemoprophylaxis in healthy children or adults based on potential exposures in the community, school, camp, etc.
4. Chemoprophylaxis generally is not recommended if more than 48 hours have elapsed since the last contact with an infectious person.

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1. http://www.cdc.gov/h1n1flu/recommendations.htm
2. This is an abbreviated list. See above web-site for the full printed version.