ASK DR. BAUGHAN                                             November 24, 2000

INFLUENZA TREATMENTS

The influenza vaccine remains in short supply.  The health providers in the community continue to wait for the manufacturers to try to make up for their delay in production.  The vaccine will still be useful in minimizing the impact of influenza if people get vaccinated by mid-December.  However, since the possibility exists of many people not getting immunized, I would like to review the current treatments for influenza and their effectiveness.

There are four medicines on the market to treat influenza A and B.  None of them kill the viruses.  They all work by suppressing the multiplication of the viruses.  They all must be started within 48 hours of onset of the illness.  None of them are terribly impressive for eliminating symptoms promptly, but results of treatment are reported by average duration of symptoms, and most people remember their worst episode.  The average duration of illness requiring rest is 5 days and 3 lost days of school.  Most people would expect “the flu” to make them sick much longer.  All of the medicines, on average, reduce the duration of symptoms by 1-1.5 days.  It is harder to get good research on how much they reduce the severity of flu symptoms.

The most impressive results, though, are on the reduction of complications of influenza that require antibiotic treatment for bacterial secondary infections.  This is similar to the benefits of vaccination.  Vaccination is much more cost-effective in reducing hospitalizations and deaths in the high risk groups than it is in preventing influenza in the general population.  The medicines reduce the risk of bacterial complications by 50% in high-risk groups.  This is all a way of clarifying what insurance you are buying if you seek influenza treatment.

The four medicines fall in two categories.  The older pills, Symmetrel (amantadine) and Flumadine (rimantidine) must be taken for 10 days, even if the person is feeling better after 5 days.  Their costs are $21 and $35 dollars respectively for a course of treatment at a local pharmacy.  These medications are usually well tolerated, but may cause upset stomach and sometimes nervous agitation (Symmetrel is also used for Parkinsons disease).  Relenza (zanamivir) and Tamiflu (osetamivir) are newer products that work by inhibiting an enzyme the virus makes that allows it to break out of one cell and multiply.  Relenza is not absorbed well as a pill, so it is taken as a powder nasal spray once a day for 5 days at a cost of $52.  Tamiflu is a pill taken once a day for 10 days at a cost of $65.  Its side effects may include nausea, vomiting, and headache (which a person may already have from the flu).

Currently Relenza and Tamiflu are only approved by the FDA for treatment of influenza.  There are some research studies using them as prophylaxis for the flu, taking them daily for 6 weeks through the peak of flu season.  Current evidence indicates they may be 67-74% respectively in preventing the flu, and over 84% effective in preventing fever or severe cases.  Given the prices above for short courses, you can calculate how preventive treatment is beyond the reach of most budgets and not covered by insurance or Medicare.

Finally, how do you tell within 48 hours if you are coming down with influenza A, B or one of the over 100 types of respiratory viruses?  There are some rapid lab tests, but they are not terribly reliable.  In research on these medicines, three criteria were used:  (1) Fever of 100.4 degrees or higher (2) at least one respiratory symptom - runny nose, cough, shortness of breath, etc. (3) one constitutional symptom - fatigue, aching, “feeling like a truck ran over me,” “lousy all over,” etc.  And, of course, that one very important way to minimize risk of spread - wash your hands frequently.