Vaccination and Treatment

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Protect Yourself from Influenza

The best way to protect yourself from influenza is to receive an annual influenza immunization. The influenza vaccine is an inactivated (killed) viral vaccine.

To manufacture the vaccine, influenza viruses are grown in chicken eggs, harvested, and then killed through chemical means. The vaccine is then purified and tested for purity, safety, and its ability to stimulate protective antibody in humans.

The strains which are chosen to be included in the vaccine are those which scientists have determined will be the predominant strains during the current influenza season.

Effectiveness of Influenza Vaccine

No vaccine is 100% protective and influenza vaccine is no exception. To a certain extent, the effectiveness of the vaccine in a particular year depends on how well the strains used to make the vaccine "match" the strains that are causing illness. When the match is a good one, the effectiveness can be expected to be higher. Influenza vaccine can prevent symptoms of influenza in 70% to 90% of healthy young adults. However, the vaccine’s effectiveness in preventing influenza may be as low as 30% to 40% in very frail elderly persons. This is because elderly persons have less ability to make protective antibodies. However, even in these elderly and frail people, influenza vaccine has been shown to significantly protect against the severe complications of influenza: hospitalizations and death. So even if the vaccine cannot protect these persons from influenza illness, it may protect them from severe illness and death.

Get the Influenza Vaccine in the Fall

Since influenza activity in the United States usually peaks in the winter, most influenza vaccination programs are conducted in October through November of each year, which is the best time for you to plan on getting the vaccine. However, because epidemics sometimes do not occur until March or April, you can get the vaccine anytime during the winter months, although fall time is the best time to get the vaccine.

The vaccine is given with a half-inch to one-inch needle. About one-tenth of a teaspoon of fluid is administered in the upper arm muscle of older children and adults. Only one shot is needed for older children and adults. Previously unvaccinated children aged less than nine years may require two doses given one month apart.

Get the Influenza Vaccine if....

The Advisory Committee on Immunization Practices or ACIP is the official committee responsible for making vaccine recommendations in the United States. ACIP recommends that all persons aged 50 years or older be vaccinated with influenza vaccine every year, unless there are strong reasons not to (see below). In addition, certain other individuals or groups of individuals should receive an annual influenza vaccination (see Who Should Get Vaccinated).

The Influenza Vaccine is Safe

The influenza vaccine is a safe and effective vaccine. You cannot get influenza by receiving an influenza shot with the inactivated vaccine.

As with almost any type of medication or medical procedure, there may be side effects of the vaccine. The most common type of side effect is soreness at the injection site. Soreness can last up to two days, is mild, and rarely will impair daily activities.

Fever, malaise, muscle aches, and other symptoms can occur in persons with no previous exposure to the influenza virus used to make the vaccines, for example in children. Symptoms occur 6-12 hours following influenza vaccination and usually last one or two days. Recent studies in elderly persons and healthy young adults, using a type of vaccine called "split-virus influenza vaccine," show no increase in these symptoms.

In addition to the side effects noted above, a number of other rare side effects may occur.

Allergic reactions may rarely occur after influenza vaccination and are thought to be due to small amounts of egg protein which may remain in the vaccine after purification. If you are allergic to eggs you are at risk of developing an allergic reaction to the vaccine (see below).

Guillain-Barre Syndrome (GBS) is a condition affecting the nervous system which results in paralysis. Recovery is complete or nearly complete in about 85% of cases. An average of 6% of persons with GBS will die. The cause of GBS is unknown and about 10 to 20 cases per one million adults occur each year in the United States. The precise risk of GBS associated with current influenza vaccinations is unclear, but some studies estimate that the risk may be 1-2 cases per one million vaccinations. Since the annual rate of influenza related complications is so high, the potential benefits of influenza vaccination clearly outweigh the small possible risks of vaccine-associated GBS*

* The annual rate of influenza related hospitalization ranges from 200 to 300 hospitalizations per million persons aged 5 - 44 years, and 2,000 to over 10,000 hospitalizations per million persons aged 65 years and older. The annual rate of influenza related death ranges from 300 to over 1,500 deaths per million persons 65 years and older.

Who Should Not Get the Influenza Vaccine

While the influenza vaccine is safe for almost everyone, there are a few reasons why someone should not receive the influenza vaccine.

If you are allergic to eggs and you are at high risk of developing complications should you get influenza, you should discuss this with your physician as several options are available such as egg desensitization or anti-viral medications. Other conditions are listed in the Who Should Not Get Vaccinated link.

Treating Influenza and Influenza Symptoms

Four anti-influenza drugs are available to prevent or treat influenza A. Two of these drugs, called amantadine and rimantadine, are available only by prescription from your physician. Amantadine and rimantadine are not effective against influenza B or influenza C.

Either of these medications can be used to prevent influenza A if they are taken before exposure to the virus or, if you have been exposed, before symptoms develop. They may also be used to treat influenza but they must be given within 48 hours of developing symptoms. They act by decreasing the severity of illness and decreasing the duration of illness. Both of these drugs may produce undesirable side effects. Certain side effects, such as light-headedness and difficulty concentrating, are more common with amantadine. Your physician can discuss these side effects with you.

The US Food and Drug Administration approved two new drugs in 1999 that are effective for the treatment of both influenza A and influenza B. These drugs, called neuraminidase inhibitors, block the normal function of the viral neuraminidase. Both drugs are available only by presecription. One of the drugs, zanamivir (Relenza®, Glaxo Wellcome Inc.) is inhaled as a powder twice a day for 5 days. A special device called a diskhaler is supplied with the medication. The other drug, oseltamivir phosphate (Tamiflu ^TM, Roche Pharmaceuticals), is a tablet that is taken by mouth twice a day for 5 days. Both zanamivir and oseltamivir phosphate should be used within 48 hours of onset of symptoms. Studies are now ongoing to determine if zanamivir and oseltamivir phosphate can be used to prevent influenza A and influenza B.

Should you develop influenza, the symptoms can be treated to minimize discomfort. Fever and muscle aches may be treated with aspirin, acetaminophen or ibuprofen. Only adults 18 years of age and older should use aspirin however, because of the possibility of children developing a severe liver and central nervous system condition called Reye Syndrome.

Adequate liquids and nutrition are necessary to prevent dehydration and for rapid recovery.

Some bed rest is necessary and helpful in recovery. Avoid overexertion when you are experiencing symptoms.

What To Do If You Develop Influenza