Is there any treatment for the flu?

Flu vaccine

Much of the illness and death caused by influenza can be prevented by annual influenza vaccination. Flu vaccine (influenza vaccine made from inactivated and sometimes attenuated [non-infective] virus) is specifically recommended for those who are at high risk for developing serious complications as a result of influenza infection. These high-risk groups include all people aged 65 years or older and people of any age with chronic diseases of the heart, lung or kidneys, diabetes, immunosuppression, or severe forms of anemia.

Other groups for whom vaccine is specifically recommended are residents of nursing homes and other chronic-care facilities housing patients of any age with chronic medical conditions and children and teenagers who are receiving long-term aspirin therapy and who may therefore be at risk for developing Reye syndrome after an influenza virus infection. Influenza vaccine is also recommended for people who are in close or frequent contact with anyone in the high-risk groups defined above. These people include health-care personnel and volunteers who work with high-risk patients and people who live in a household with a high-risk person.

Because the flu is easily spread among children and because many children require hospitalization with the flu, the U.S. Centers for Disease Control and Prevention (CDC) now advises that all children ages 6 to 59 months receive a yearly flu vaccination.

Although annual influenza vaccination has long been recommended for people in the high-risk groups, many still do not receive the vaccine. Some people are not vaccinated because of misperceptions about influenza and the vaccine. They mistakenly perceive influenza as merely a nuisance and believe that the vaccine causes unpleasant side effects or that it may even cause the flu. The truth is that influenza vaccine causes no side effects in most people. The most serious side effect that can occur after influenza vaccination is an allergic reaction in people who have severe allergy to eggs, since the viruses used in the vaccine are grown in hens' eggs. For this reason, people who have an allergy to eggs should not receive the influenza vaccine. Also, the vaccine is not recommended while individuals have active infections or active diseases of the nervous system.

Less than one-third of those who receive the vaccine have some soreness at the vaccination site, and about 5% to 10% experience mild side effects, such as headache or low-grade fever, for about a day after vaccination. These side effects are most likely to occur in children who have not been exposed to influenza virus in the past.

Nevertheless, some older people remember earlier influenza vaccines that did, in fact, produce more unpleasant side effects. Vaccines produced from the 1940s to the mid-1960s were not as highly purified as modern influenza vaccines, and it was these impurities that caused most of the side effects. Since the side effects associated with these early vaccines, such as fever, headache, muscle aches and fatigue, were similar to some of the symptoms of influenza, people believed that the vaccine had caused them to get the flu. However, influenza vaccine produced in the United States has never been capable of causing influenza. One type of influenza vaccine made with live attenuated influenza viruses has been developed, but this vaccine is made with viruses that can confer immunity but do not cause classic influenza symptoms.

Some people do not receive influenza vaccine because they believe it is not very effective. There are several different reasons for this belief. People who have received influenza vaccine may subsequently have an illness that is mistaken for influenza, and they believe that the vaccine failed to protect them. In other cases, people who have received the vaccine may indeed have an influenza infection. Overall vaccine effectiveness varies from year to year, depending upon the degree of similarity between the influenza virus strains included in the vaccine and the strain or strains that circulate during the influenza season. Because the vaccine strains must be chosen nine to 10 months before the influenza season, and because influenza viruses mutate over time, sometimes mutations occur in the circulating virus strains between the time the vaccine strains are chosen and the next influenza season ends. These mutations sometimes reduce the ability of the vaccine-induced antibody to inhibit the newly mutated virus, thereby reducing vaccine efficacy.

Vaccine efficacy also varies from one person to another. Studies of healthy young adults have shown influenza vaccine to be 70% to 90% effective in preventing illness. In the elderly and those with certain chronic medical conditions such as HIV, the vaccine is often less effective in preventing illness. Studies show the vaccine reduces hospitalization by about 70% and death by about 85% among the elderly who are not in nursing homes. Among nursing-home residents, vaccine can reduce the risk of hospitalization by about 50%, the risk of pneumonia by about 60%, and the risk of death by 75% to 80%. If antigenic drift results in changing the circulating virus from the strains used in the vaccine, vaccine efficacy may be reduced. However, the vaccine is still likely to lessen the severity of the illness and to prevent complications and death.