Flu Shots for Elderly, Infants AdvisedYou know it when you have it. The fever, the aches, the stuffy or runny nose and general state of misery that can keep you bedridden for days. When the flu bug bites, there is often no escape.
The name influenza comes from the 18th century Italians, who blamed the disease on the influence of heavenly bodies. New strains of influenza appear periodically, at irregular intervals, causing worldwide pandemics. There have been 31 documented influenza pandemics since the first recorded pandemic of 1580, including three pandemics during the 20th century -1918, 1957 and 1969. The Spanish Flu in 1918-1919, was particularly virulent, killing an about 40 million worldwide.
Influenza, commonly called "the flu," is an infection of the respiratory tract caused by a virus. The virus is spread through airborne droplets of respiratory fluids when a person coughs or sneezes. Compared with most other viral respiratory infections, such as the common cold, influenza infections often cause more severe illnesses. Typical symptoms include fever and respiratory problems, such as coughing, sore throat, and sinus congestion. Headaches, muscle aches and extreme fatigue are other symptoms. Sometimes the flu causes nausea, vomiting and diarrhea, especially in children, but these symptoms are rare.
Most flu victims recover in one to two weeks, but some people develop serious and potentially life-threatening complications such as pneumonia. In an average year, influenza is associated with more than 20,000 deaths and more than 100,000 hospital cases, according to the US Center for Disease Control and Prevention (CDC).
While flu-related complications can occur at any age, the elderly and those with chronic health problems are most susceptible. An annual influenza vaccination can prevent much of the illness, and greatly reduce the risk of death from influenza. The vaccine is specifically recommended for people who are at high risk. While the National Institute of Health in Korea recommends influenza vaccinations for those 65 or older, CDC this year lowered the age of the high-risk group to 50 or older.
People of any age with chronic heart, lung or kidney disease, diabetes, immuno-suppression, or severe forms of anaemia; and children and teenagers, aged six months to 18 years are included in the high-risk category. Those on long-term aspirin therapy, and women who will be in their second or third trimester of pregnancy during the influenza season, are also at greater risk.
Although an annual influenza vaccination has long been recommended for people in high-risk groups, many still do not get the vaccine.
Overall vaccine effectiveness varies from year to year, depending on which virus strains the vaccine covers and which strains circulate each season.
Vaccine effectiveness also can depend on a person's age. Studies of healthy young adults have shown the influenza vaccine to be 70-90 percent effective. In the elderly and those with chronic conditions, the vaccine is often less effective in preventing flu, but can reduce the severity of the illness and the risk of serious complications and death.
Despite the benefits of the influenza vaccine, there are some people who should not get the shot. People who are allergic to eggs, those who have had a serious reaction to an influenza shot, and anyone with a temperature should not get vaccinated.
Although it is made from a virus, the influenza vaccine will not give you the flu, per se. The vaccine recipient's immune system is stimulated and antibodies built up without causing the actual disease.
Because flu viruses constantly mutate, influenza vaccines must be modified each year. An international network to monitor outbreaks of influenza consists of 110 centers in 82 countries and four World Health Organization (WHO) Collaborating Centers for Reference and Research on Influenza - in Atlanta, London, Melbourne and Tokyo.
Results are reviewed each February and September, and the organizations recommend the composition of the following year's vaccine. The vaccine for the 2000-2001 flu season contains three strains of influenza - Type A Moscow, Type A New Caledonia and Type B Beijing.
The vaccine is grown in eggs. A microscopic droplet of the influenza virus is injected into an air sack above the embryo. In two to three days, the original droplet becomes larger and is ready to be harvested. The top of the egg is taken off and the virus is removed.
In Korea - where flu season peaks from December to February - it is recommended that people get vaccinated by mid-November. This is because it takes two weeks to build up immunity. A flu shot is effective for up to six months.
This season, there is expected to be a shortage of vaccines. About eight million people were vaccinated last year, but so far this year, there is only enough vaccine for about six million people. However, NIH officials estimate this should be enough to cover those at high risk.
By Kim Hoo-ran
by Kim Hoo-ran