Avoiding The Flu

by Food and Drug Administration (FDA)

Though flu is expected to make its usual rounds this winter, many Americans won't have to suffer its high fever, characteristic cough, and possibly serious complications. A safe, effective vaccine is available.

It was not always so.

In 1918-1919 — during the worst flu epidemic of all time — doctors had meager resources to fight the disease. To relieve symptoms, they relied on aspirin and other simple remedies. An influenza vaccine and antibiotics to combat pneumonia and other flu complications were years away from development. It has been estimated that over 20 million people died and possibly half the world's population came down with the flu in this global epidemic, or pandemic.

Influenza epidemics spread quickly through large populations because flu viruses are highly contagious. During flu's acute phase, respiratory tract secretions are rich in infectious virus and the disease is transmitted easily by sneezing and coughing. The incubation period lasts one to three days. Then symptoms — such as chills and fever that develop within 24 hours, headache often accompanied by sensitivity to light, sore muscles, backache, weakness, and fatigue — appear suddenly. Respiratory tract symptoms may be mild at first with a dry, unproductive cough, scratchy sore throat, and runny nose. As the person's temperature rises — sometimes to as high as 104 degrees Fahrenheit — the muscle aches and headache get worse, and secondary bacterial infections, such as bronchitis and pneumonia, may move in. Ear infections are a common complication in children.

With no complications, acute symptoms usually subside after two or three days and the fever ends, although it may last as long as five days. Weakness and fatigue may persist for several weeks.

Vaccine Most Important Defense

Today, we have several ways to defend people from influenza. The most important tool is immunization by a killed virus vaccine. Flu vaccines are licensed by FDA, and the exact composition of the vaccine varies each year, depending on the flu strains scientists expect to be most common. Influenza viruses have the ability to change themselves, or mutate, thereby becoming different viruses. Having the flu once does not confer lasting immunity, as is the case with some childhood viral diseases. The antibodies people produce in response to the one flu virus don't recognize and, therefore, don't provide immunity to a different flu virus. Because the immunity conferred by a flu shot lasts for only about a year — and because different flu strains may circulate each season — individuals who want to be protected from flu should be vaccinated annually.

It takes two to four weeks for antibodies to develop after the vaccine is given. Therefore, the ideal time to get the flu vaccine is mid-October to mid-November, before the start of the flu season, which lasts from about December to March in the Northern Hemisphere. (Travelers should be aware that flu season lasts all year in some tropical climates, and in the Southern Hemisphere occurs from April to September.)

Who Should Get Vaccine?

Vaccination is available to anyone who wants it and whose doctor agrees it would be beneficial. The Public Health Service's Advisory Committee on Immunization Practices (ACIP) strongly recommends vaccination for:

People age 65 or older. (Effective May 1993, Medicare Part B pays for flu shots.)

People over 6 months who have underlying medical conditions that put them at increased risk for flu complications. These include:

• chronic cardiovascular disorders or lung disease, including asthma in children
• chronic metabolic diseases requiring hospitalization during the preceding year or regular checkups. These diseases include diabetes, kidney disorders, blood disorders, and impaired immune systems due to HIV infection or chemotherapy.
• Residents of nursing homes and other facilities that provide care for chronically ill persons of any age.
• Children and teenagers (6 months to 18 years of age) who have to take aspirin regularly and therefore may be at risk of developing Reye syndrome after influenza. (Children who have symptoms of flu or chickenpox should not be given products containing aspirin or other salicylates without consulting a doctor.)

To reduce the risk of transmitting flu to high-risk persons, such as the elderly, transplant patients, and people with AIDS (who may have low antibody response to the flu vaccine) — and also to protect themselves from infection — ACIP recommends vaccination for doctors, nurses, hospital employees, employees of nursing homes and chronic-care facilities, visiting nurses, and home-care providers. Students, police, firefighters, and other essential workers and community service providers may also find vaccination useful.

In most cases, children at high risk for influenza complications may receive the flu vaccine when they receive other routine vaccinations, including DTP (diphtheria, tetanus and pertussis) and pneumococcal vaccines. Pregnant women who have a high-risk condition should be immunized regardless of the stage of pregnancy; healthy pregnant women may also want to consult their health-care providers about being vaccinated.

Side Effects

The flu vaccine cannot cause flu because it contains only inactivated viruses. Any respiratory disease that appears immediately after vaccination is coincidental. However, the vaccine may have some side effects, especially in children who have not been exposed to the flu virus in the past.

The most commonly reported side effect in children and adults is soreness at the vaccination site that lasts up to two days. Fever, malaise, sore muscles, and other symptoms may begin 6 to 12 hours after vaccination and may last as long as two days.

People should be aware that they may test HIV-positive with the ELISA test after a recent flu shot, says the national Centers for Disease Control and Prevention. CDC recommends retesting with the more accurate Western Blot test to rule out false positives.

The vaccine is not for everyone. People allergic to eggs — the vaccine is made from highly purified, egg-grown viruses that have been made noninfectious — or other vaccine components should consult a doctor before getting a flu shot because they may develop hives, allergic asthma, difficulty breathing, and other allergic symptoms. The vaccine should not be given to any person ill with a high fever until the fever and other symptoms have abated.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.