That word “flu” is thrown around frequently when we get sick. If we vomit and/or have diarrhea, we call it “the stomach flu.” When we have fever or body aches, we tell our friends we have the “flu.” In reality many of these conditions are viral illnesses but not “THE FLU.” The constellation of symptoms correctly called the flu is caused by the family of viruses known as influenza. There are two general types of influenza viruses – Type A and Type B. Typically, influenza reaches its peak incidence in the winter months, and it is not uncommon for 2 or more strains to affect the population at about the same time. According to the Center for Disease Control (CDC), two different strains of Influenza A and one strain of Influenza B are causing illness in the U.S. this year. In South Texas we are seeing primarily one of the A strains but all three have been found here too.
The flu is characterized by the abrupt onset of symptoms that include fever, body aches, headache, non-productive cough, sore throat, and runny nose. Children may have additional symptoms such as ear infections or vomiting and diarrhea. The most distinguishing feature is the abrupt onset of all these symptoms on the first day. The incubation period is 1-4 days, and often a person is contagious a day before the symptoms occur. Although flu occurs in all ages, the rate of infection is highest among children. Most people have uncomplicated flu which resolves in 3-7 days. Children less than the age of 5, the elderly, and those individuals with underlying medical conditions are at the highest risk for complications of the flu. Some of these complications include pneumonia, an exacerbation of an underlying medical condition such as asthma, or a superimposed bacterial infection.
So if you or your child develops flu-like symptoms, what should you do? The mainstay of treatment remains symptomatic – control the fever with acetaminophen and/or ibuprofen (never use aspirin for it has been correlated with the development of severe condition called Reyes syndrome); keep hydrated with fluids, and rest. There are four medications that are effective against the influenza virus, but two of them are only effective against Influenza A and are not commonly used. The two that are effective against both types A and B are Zanamivir (Relenza®) and Oseltamivir (Tamiflu®). Zanamivir is an inhaled medication that is not approved for use in children under the age of 7. Oseltamivir can be used even in infancy. These mediations do not kill the virus, but only slow down its replication. As the virus infects a person, it replicates inside the body producing the symptoms. That makes starting the medicine as soon as possible so important before the virus has an opportunity to “take off.” If started within 24 hours of the onset of the symptoms, the length of the illness can be shortened by as much as 3.5 days. If started between 24 and 48 hours after the onset of symptoms, the duration is only one day less. The “horse is out of the barn” if started after 48 hours. Studies show starting these medications after 48 hours provides no benefit. Seeing the doctor early after the onset of the symptoms is most important for those at greatest risk for complications (children under age 5, the elderly, and those with underlying medical conditions).
Like in all viral illnesses, the best treatment is prevention. Although not a panacea, the flu vaccine is the best thing available to prevent getting the flu. Although if varies, estimates indicate that the vaccine is only about 60% effective in preventing the flu each year. Why is that? The influenza virus frequently mutates or changes making it necessary to produce a new vaccine each year. Medical scientists carefully plan for the changes that may occur and what viral strains will impact the next season. On occasion the virus changes significantly in ways not anticipated so the vaccine is no longer effective against the strain that causes the illness that year. The second factor in the lack of effectiveness is that no vaccine works the same in all people. Some people respond better to the make-up of the vaccine better than others. Therefore, some people do not get a sufficient immune response to provide protection. However, lack of response one year does not mean the vaccine will not work the next since it will have a different make-up.
All individuals older than 6 months should get a yearly flu vaccine. Children between the ages of 6 months and 8 years who have not previously been immunized against influenza should receive two doses administered at least one month a part. The injectable vaccine is a killed virus and cannot cause the flu. Its main side effects are redness and soreness at the site of the injection. Unlike the injectable vaccine, the vaccine administered via the nasal spray is a live but weakened virus. The side effects of the intranasal vaccine are runny nose, wheezing, headache, muscle aches and low grade fever. This weakened virus in the intranasal vaccine can be spread to others who are in close contact. Since it is a live vaccine, it is not recommended for persons who are immune compromised or to their household members. If you have not had your flu vaccine, get one today before it is too late.
For additional information about the influenza virus, a great resource is www.cdc.gov/flu.