Frequently Asked Questions: Flu (Influenza)

Group 1: People who are risk for getting a serious case of influenza or a complication should get the vaccine. This includes:

• all people 65 years of age or older
• residents of long term care facilities housing persons of any age with chronic medical conditions
• any child or adult, including pregnant women, who has a serious long-term health problem with heart disease, anemia, lung disease, kidney disease, a metabolic disease such a diabetes, or asthma; AND in the past year had to see a doctor regularly or be admitted to the hospital.
• people who are less able to fight infections because of a disease they were born with, infection with HIV, treatment with drugs such as long-term steroids, or cancer treatment with x-rays or drugs
• children and teenagers 6 months to 18 years old on long-term aspirin treatment who, if they catch flu, could develop Reye's syndrome which causes coma, liver damage, and death
• women who will be more than 3 months pregnant during the influenza season

Group 2: Anyone who has close contact with people who are at risk for getting a seriouscase of influenza. This includes:

• anyone- including children- who live with people in high risk groups (Group 1)
• health care workers (doctors, nurses, hospital and medical staff)
• personnel of nursing homes or chronic care facilities
• people who provide home care to high risk persons, such as visiting nurses and volunteers

Group 3: In addition an influenza shot may be given to:

• persons who provide important community services
• people in schools and colleges, to prevent outbreaks
• people going to the tropics any time of the year or to countries south of the equator between April and September
• breastfeeding mothers (breastfeeding does not adversely affect immune response and is not a contraindication for vaccination)
• anyone who wants to reduce their chance of catching influenza

People who need the vaccine should get it ever year. The vaccine begins to protect you after 1 to 2 weeks and protection may last up to one year. Influenza is most common in the US from December to April, so it is best to get the vaccine between September and mid-November.

Influenza vaccine can be given at the same time as any other vaccines, including pneumococcal vaccine. It should be given in a different limb.

Although only a few different influenza viruses circulate at any given time people continueto become ill with the flu throughout their lives. The reason for this continuing susceptibility is that influenza viruses are continually changing, usually as a result of mutations in the viral genes.

Currently, there are three different flu virus strains, and the vaccine contains viruses representing each strain. Each year the vaccine is updated to include the most current flu virus strains. The fact that influenza viruses continually change is one of the reasons vaccine must be taken every year. Another reason is that antibody produced by the host is response to the vaccine declines over time, and antibody levels are often low one year after vaccination.

Because the viruses change often, they may not always be covered by the vaccine. But people who do get influenza after getting the vaccine often have a milder case than those who did not get vaccinated.

Also, other viruses cause diseases that seem like influenza, and the flu vaccine does not protect against these other viral infections.

As with any medicine, there are very small risks that serious problems, even death, could occur after taking the vaccine. The risks from the vaccine are much smaller than the risks from the disease if people stopped using the vaccine. Almost all people who get influenza vaccine have no serious problems from it. The viruses in the vaccine are killed, so you cannot get influenza from the vaccine.

If mild or moderate problems occur, they usually start soon after vaccination and can last 1-2 days. Less than one-third of those who receive vaccine have some soreness at the vaccination site, and about 5-10% experience other mild side effects. Side effects are most likely to occur in children who have never been exposed to flu virus. Symptoms mayinclude:

• soreness, redness, or swelling where the shot was given
• fever
• aches

Although annual flu vaccination has long been recommended for people in 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 flu as merely a nuisance and believe that the vaccine caused 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 flu 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 influenza vaccine.

Tell your health care provider if you ever had a serious allergic reaction or other problems after getting influenza vaccine, if you were ever paralyzed by Guillain-Barre Syndrome, or if you now have a moderate or severe illness.