Last Updated:
June 2003


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by Len Leshin, MD, FAAP

Copyright 1996-2002, All rights reserved
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The Virus

The flu has been known since ancient times. The word "influenza" comes from the Italian astrologers who thought the flu was due to the "influence" of the heavenly bodies. In fact, it's not very heavenly at all. The worst epidemic for the most people killed in the shortest time was the Spanish Flu in 1918-19, killing 27 million people world-wide in just 18 months (by contrast, World War I had killed 9 million men in 4 years).
Send Me Email The flu virus comes in two main flavors: type A and B. Each winter, one type usually predominates over the other quite a bit. Type A is usually the more severe, but there are exceptions.

The virus is notorious for mutating. Usually, these are subtle changes that only involve the virus' outer coat, which most people's immune system can effectively handle; but every ten to twenty years a major change occurs, leaving the population vulnerable to the infection as well as pneumonia, which quite frequently follows the flu. These subtle mutations are the reason why we need yearly vaccinations, rather than one vaccine giving long-term protection.

The flu virus is spread by direct contact, sneezing and coughing, or articles recently contaminated by direct contact. During an outbreak, the highest attack rates occur in schools and office buildings. Infected people are most contagious during the 24 hours before symptoms occur, but are also contagious throughout the course of the illness. The incubation period (the time from when you become exposed to when you get sick) is about 3 days.

The Infection

Community epidemics can last 4 to 8 weeks, but the peak is usually 2 weeks after the beginning of the epidemic. The flu is hardest on children, the elderly, and people with chronic illnesses that already put strain on the immune system.

Signs and symptoms: sudden fever, chills, an all-over achiness, and burning of the eyes is common. Some flu varieties affect the respiratory tract more, causing nasal drainage, cough and sore throat. Other flu varieties cause more intestinal symptoms, such as nausea and vomiting. The length of illness is usually 5 to 7 days. Because influenza can quite frequently lead to pneumonia, a cough and fever for more than 5 days should be investigated by a physician. Croup can also be associated with the flu in younger children. Flu is often worse in children with chronic lung or heart diseases.

If you can catch it in the first 48 hours, there are medications for influenza that can shorten the duration of illness. The antiviral medications amantadine (Symmetrel) and rimantidine (Flumadine) are very useful for treating type A influenza, but not type B. Amantadine has gone generic and is cheaper, but has the more frequent side effect of hallucinations. Amantadine is not recommended in people who have epilepsy. Both can be used in children over 1 year of age. Neither is effective against type B flu. If influenza A is diagnosed in a member of a family, either amantadine or rimantidine may be given to other household members over 1 year of age as a prophylaxis.

In 1999, a new anti-influenza drug was introduced into the US called Relenza (zanamavir) for adults and children 12 years of age and older. Relenza is a powder that is inhaled and is useful against both type A and type B, but it must be started within 48 hours of the first symptoms to be effective. Relenza is also effective as a preventitive treatment for people exposed to family members with influenza. A similar drug, Tamiflu (oseltamivir), is now available in both a pill and oral suspension, and is now indicated for children 1 year of age and older for both types A and B. Tamiflu may be used as a preventative for people aged 13 years and older.

Occasionally, an inflammation of the muscles ("myositis") will develop several days after the flu. This is especially seen in the calves, and can last 3 to 4 days. Reyes syndrome, a devastating disease of the liver and brain, has been associated with the use of aspirin and influenza; acetaminophen or ibuprofen should be used instead.

The Vaccine

Each spring, the Center for Disease Control analyzes the recent years' strains and predicts which strains might hit the US that winter; and they've been more accurate than not.

Children as young as 6 months of age can get the flu vaccine. If the child is less than 9 years of age, the first year the child gets the flu vaccine, the child will need 2 shots, 1 month apart. If the child is 9 years or older the first year, 1 shot is enough. It takes 10 to 14 days from the time of vaccination to full immunity. The flu vaccine is estimated to protect fully 7 out of 10 children who get the vaccine. The other 3 get milder cases.

Children who are at high risk from serious complications from the flu should get the vaccine every year. This category includes children with the following diseases or conditions: asthma, bronchopulmonary dysplasia or other chronic lung diseases; heart diseases; sickle-cell anemia or other hemoglobinopathies; HIV or other immunosuppressive diseases; diabetes mellitus; chronic kidney diseases; chronic metabolic diseases; children getting immunosuppressive drugs; children taking long-term aspirin therapy.

Children and adults who are close contacts of high-risk children should also be vaccinated. This includes hospital personnel and other health care workers, and household contacts of high-risk children.

The Center for Disease Control also advocates the vaccine for anyone in whom getting the flu would result in a major "disruption of routine activities." I'm trying to figure out if that phrase leaves anyone uncovered. Personally, I do recommend the vaccine for all children attending school or daycare.

Side effects: the main one is a sore arm from the injection. Infrequent fevers, achiness and local redness can occur, usually within the 24 hours after vaccination. The whole virus vaccine causes more side effects than the split-virus (subviron) version, so the split virus version is recommended for children 12 years and younger. Children who get anaphylactic reactions to eggs (severe hives and difficulty breathing) should not get the vaccine. The manufacturers of the vaccines suggest not giving the vaccine to anyone sick with a respiratory illness at the time of the clinic visit.

The vaccine is usually given from October to November, in time for the flu season which usually starts in early December (it starts earlier in Alaska and Hawaii).

A nasal spray flu vaccine (FluMist,TM) was approved by the US FDA in early 2003 for use in individuals ages 5 to 49 years. It is very effective, and most insurance companies cover it now.

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