Influenza and the Flu Vaccine

What is influenza?
What are the symptoms of the flu?
What are the complications of influenza?
How does the flu vaccine work?
Who should get the flu vaccine?
When is the flu vaccine given?
What types of flu vaccines are available this year?
What are common side effects of the flu vaccine?
Who should NOT get the flu vaccine?
What if a person is allergic to eggs?
What if someone still gets the flu?
This Year's Flu Season
What about the pneumococcal vaccine?

What is influenza?

Influenza, also known as the “flu,” is an infection of the respiratory system that is caused by the influenza virus. Influenza season peaks between late December and March. The flu is responsible for an average of 36,000 deaths every year in the U.S.

What are the symptoms of the flu?

Symptoms of the flu typically begin very quickly. Symptoms often include muscle aches, feeling very tired, high fever with chills, headache, cough, sore throat and runny or stuffy nose. Stomach related symptoms such as nausea, vomiting and diarrhea are often not associated with the flu. Most people recover from the flu in 1 – 2 weeks. However, some people, especially the very young and the elderly, can have flu-related complications that can be serious.

What are the complications of influenza?

In some people, the flu can lead to serious complications. Some people develop influenza pneumonia or a secondary bacterial pneumonia. People with asthma and other chronic lung diseases may have worsening of respiratory symptoms that require stronger treatment. They also have a higher risk of developing pneumonia from influenza. Other complications include Reye's syndrome , myositis (muscle inflammation) and Guillain-Barre syndrome. Myocarditis and pericarditis, which affect the heart, have also been linked to the flu.

How does the flu vaccine work?

Fortunately, the flu vaccine can prevent many of the illnesses and deaths associated with the flu. The flu vaccine contains either killed or weakened influenza viruses that cause your immune system to develop antibodies. It takes two weeks to build an adequate level of antibodies to protect against the flu. When you are exposed to the flu, these antibodies then fight off the viruses. While the vaccine does not always prevent the flu, the vaccine reduces the risk of complications and the severity of the illness.

Who should get the flu vaccine?

Most people benefit from receiving the flu vaccine. It is strongly recommended for people who are at high risk for complications of the flu. Also, people who can give the flu to those who are at high risk should be vaccinated.

A yearly flu vaccine is strongly recommended for the following groups:

• All children aged 6 to 23 months
• Adults aged 65 and over
• Nursing home residents
• Adults or children with chronic illnesses
• People with chronic respiratory diseases such as asthma, COPD (emphysema, chronic bronchitis) cystic fibrosis or bronchiectasis
• People who have a suppressed immune system
• Children and teens on long-term aspirin therapy
• Healthcare providers
• Women who will be pregnant during the flu season
• Household members of people in high risk groups

A new recommendation last year was that healthy children aged 6-23 months should be given the flu vaccine, when possible. The vaccine is safe for children six months of age and older. The first time children under nine years of age are vaccinated, they should be given two doses one month apart.

When is the flu vaccine given?

Each year the flu vaccine is developed with three strains of influenza virus. These strains have been identified as the cause for the illness in the upcoming year. The flu vaccine must be given every year for protection against the flu. The best time to receive the vaccine is October through November.

What types of flu vaccines are available this year?

This year two influenza vaccines are available. One is the standard “flu shot” that contains killed influenza viruses. The flu shot has been given for many years and is approved for infants aged 6 months and older, children and adults. It is the preferred vaccine for people who have chronic illness, a weakened immune system, healthcare providers and pregnant women.

The other vaccine, a nasal spray, became available last year. It contains live, but weakened viruses. It is recommended only for healthy children and adults aged 5 to 49 years. Because the spray uses a live virus, it still needs to be studied for possible side effects in other groups, such as older people, young children and those with chronic illness or a weakened immune system.

What are common side effects of the flu vaccine?

The flu vaccine is safe for almost everyone. Because the vaccine is made from killed or weakened viruses, a person cannot “get” the flu from the vaccine. Some people experience a few minor side effects from the flu shot. These can include: redness or pain at the area of the shot, soreness, headache and a low-grade fever for a few days. When the swine flu vaccine was given in 1976, more serious side effects, such as Guillain-Barre Syndrome , were reported. There has been no increased incidence of Guillain-Barre Syndrome since that time.

There has been some concern about reactions to Thimerasol, the preservative in the flu shot. It is used at a very small amount and has not been shown to be a problem. However, if you are concerned about Thimerasol, you can check with your doctor about “preservative free” flu vaccine.

Reported side effects from the nasal spray are runny or stuffy nose, cough, sore throat, chills, fever, headache and occasional vomiting (in children).

Who should NOT get the flu vaccine?

There are certain groups of people who should check with their doctor before getting a flu vaccine. These include:

• People who have had a severe reaction to a flu shot in the past
• People who developed Guillain-Barre Syndrome 6 weeks after getting a flu shot
• People who have a severe allergy to egg

What if a person is allergic to eggs?

Because the flu vaccine has been grown on egg protein, the flu vaccine is not recommended for people who have a history of severe egg allergy. However, if you have been able to eat eggs, it may be possible for you to receive the flu vaccine. Many people who believe they are allergic to eggs tolerate the flu vaccine. At National Jewish, these people are first skin tested to egg and then to the vaccine. If the testing is negative, the vaccine is given in our clinic and the person is watched closely. For some people who are allergic to the vaccine, it can be given in smaller doses under close supervision. This can require several shots over many hours. This is only done when the person is at high risk for complications of the flu.

What if someone still gets the flu?

Treatment with antiviral medicine is available when someone gets the flu. These medicines help lessen the symptoms and the length of time a person is ill. Antiviral medicines must be started within the first two days after symptoms begin. These medicines include:

• Symmetrel®(amantadine)
• Flumadine®(rimantadine)
• Relenza®(zanamivir)
• Tamiflu® (oseltamivir)

This Year's Flu Season

This year there is a shortage of flu vaccine. We recommend that you call your doctor to learn where you can receive the vaccine. You can also check with your local public health clinic or state health department immunization program.

What about the  pneumococcal vaccine?

The pneumococccal vaccine can lessen the chance of pneumococcal pneumonia, which can occur as a major complication of the flu or without the flu. The pneumococcal vaccine, however, is not a substitute for the flu vaccine. Pneumococcal vaccine helps to protect someone from strains of bacterial pneumonia. It is generally recommended for many of the same high-risk people for whom influenza vaccine is recommended. People with emphysema/COPD, congestive heart failure, cirrhosis, renal failure, diabetes or Hodgkin's disease should be given the pneumococcal vaccine. In addition, people over age sixty-five and those with asymptomatic HIV infection should receive the vaccine. Native Americans are also at increased risk and should receive the vaccine. The pneumococcal vaccine is given every five to seven years. It is safe to receive both the influenza and pneumococcal vaccines at the same time.

Learn more about pneumonia, its diagnosis, treatment, and more.

This information has been approved by Gwen Huitt M.D. (January 2005).