The "Flu"

December 3, 2003

By David Dunnington, MD

With the coming of winter you hear advice from health care providers, the news media, health insurance companies, and many employers to have a “flu shot” to protect yourself. What is this “flu” that has so many people worried and lining up at doctor’s offices, employee health clinics, and even grocery stores and pharmacies for this protective immunization?

In common, everyday jargon “the flu” means different things to different people. It seems as though anything that makes a person feel out of sorts, either mildly or severely, (and particularly if symptoms include stomach upset and diarrhea) will be called “the flu”. I advise my office staff, “When someone calls and complains of ‘the flu’ it could be anything from a heart attack, to appendicitis, to a simple cold!” To most people flu means the “stomach flu” with its sudden onset of nausea, vomiting, and diarrhea, usually with mild to moderate fever. This illness is really “viral gastroenteritis”. These many ills we commonly term “flu” are usually not influenza and the “flu” shot will not provide protection.

The real “flu” is an acute viral illness caused by influenza A or B virus. The onset of illness is usually rapid, with initially mild symptoms of general malaise progressing in several hours to a fever of 102F or higher. Next comes incapacitating muscles aches and pains, headache, some sore throat, and eventually a persistent, usually dry, non-productive cough. Coughing spells are usually quite painful. (Some influenza victims may have stomach upset and diarrhea but respiratory symptoms are more common.) In healthy adults and children, the symptoms gradually subside over seven to 10 days. Flu sufferers often miss an entire week of work or school.

So, why do we worry so much about influenza? First of all, it is common. There are over 20 million cases each year in the U.S. Secondly, the virus is highly contagious. Most importantly, elderly folks, and adults and children of any age with serious medical problems (diabetes, heart disease, emphysema, etc.) can become gravely ill. Each year in the U.S. 20,000 to 40,000 deaths are directly or indirectly linked to influenza. That is the bad news; that is why we recommend flu shots.

In the last five years, there has been increase publicity about the importance of having flu shots. The public health goal of this increased publicity is to give rise to greater “herd” immunity. The more people immunized, be they healthy or chronically ill, the fewer contacts there will be for high-risk individuals to contact influenza.

Some vaccines, like polio, can be given in childhood and create lifelong immunity. Influenza vaccines however need to be given every year. The influenza viruses change their antigenic “code” frequently. Antibodies developed to fight off previous influenza viruses do not immediately attack the new virus. This allows it to gain a toehold and spread. Fortunately for us, infectious disease specialists (called virologists) keep track of which strains are most active in different parts of the world at different times. They are able to predict which strain will be most active in any given year. The flu vaccine usually contains three strains of influenza virus – two strains of A and one of B to “cover the bases”, so to speak. Still, about every 10 to 15 years a significantly different strain will appear and cause a worldwide epidemic that is not well controlled with the flu shot.

Unfortunately, high-risk individuals do not respond as well to the flu vaccine. In these groups, the effectiveness at preventing illness completely is only 30 to 40 percent. Public health officials hope healthy folks will be immunized so they will not expose friends, neighbors, or relatives who may be at high risk. However, for elderly, very young, and high medical risk individuals, getting a flu shot will make the illness less severe. Studies show the vaccines are 50 to 60 percent effective in preventing hospitalization and 80% effective in preventing death.

Until this year (2003-2004 flu season) the only type of flu vaccine available has been serum administered with a needle and syringe. This fall a new type, administered as a nasal spray, has become available. It is different from the injectable immunizations by being a “live attenuated virus” vaccine. Because it contains “live but tamed critters” its use is restricted to healthy children and adults between five and 49 years of age. It should not be given to pregnant women. Side effects include nasal congestion, mild cough, and sometimes a low-grade fever for a day or two. Adults and children receiving this immunization must avoid contact with high-risk individuals for at least 21 days following the immunization.

The cost of regular flu shots varies from free (if insurance or employer pays), to $15 to $25 per immunization. A dose of the nasal spray vaccine costs $45 to $55. For those who have an aversion to shots, there are four approved medications that can lessen the severity and duration of the illness if started with 48 hours of the first symptoms. Some of these medicines can be given preventatively to unimmunized individuals who are exposed to the virus but have not yet developed symptoms. Costs vary from $20 to $60 for a course of treatment.

One other word of caution regarding children developing influenza, aspirin should not be used to control fever or aches and pains. Use of aspirin in this way has been linked to an increased risk of developing Reye’s syndrome, an acute central nervous system disorder causing fever, coma, and death.

Ben Franklin’s adage, “an ounce of prevention is worth a pound of cure” certainly applies to support widespread use of influenza vaccines. The cost and risk of vaccine use is low and benefits in terms of lives saved, hospitalizations prevented, and reduced absenteeism from work and school are huge. For healthy folks who do not like shots, nasal spray vaccines are now available. For those who do come down with the flu, medicines are available which may lessen the severity and shorten the course of the illness.

If you think you have the flu and seem sicker than you think you should or don’t seem to be getting better, seek help from your doctor to make sure the “flu” is not something else, or you haven’t developed complications and need other treatments.