Frequently Asked Questions About Flu and Flu Shots

What is the Flu?

Influenza, also known as "the flu", is a viral infection of the respiratory system, which includes the nose, throat, bronchial tubes and lungs. Influenza viruses are divided into three types, A, B, and C. Types A and B are responsible for nearly all of the influenza illness that occurs almost every winter. Infection with type C influenza usually causes either a very mild respiratory illness, or no symptoms at all. Types A and B are further subdivided into "strains". These are usually named after the geographic location where the strain was first discovered. An example is Influenza A Hong Kong. Different strains have variations in surface markers on the viral particle which are recognized by the human immune system. The influenza virus is able to change these surface markers from year to year through mutation. It is the constant changes in these surface markers which allows the influenza virus to evade the human immune system, and this is why an individual can become ill with influenza each flu season.

When does influenza occur?

In New Jersey, influenza typically occurs any time between October through early April. However, the peak season of occurrence is during January and February.

Who gets influenza?

Anyone can get influenza.

How is influenza spread?

Influenza is primarily spread from person to person through the air. Virus particles are released into the air through coughing and sneezing of persons who are ill with influenza. Crowded conditions in enclosed spaces provide ideal conditions for the spread of influenza.

What are the symptoms of influenza?

The symptoms of influenza are primarily fever, headache, sore throat, body aches, and a severe and often prolonged cough. Intestinal symptoms, such as cramps and diarrhea, are uncommon. What is often called "intestinal flu" is not influenza. Influenza symptoms in children are very similar to those symptoms caused by other respiratory viruses. Although most individuals are ill for only a few days to a week, some individuals have a much more serious illness, such as pneumonia, and may need to be hospitalized. Thousands of individuals die each year in the United States from influenza or influenza-related complications.

How soon do the symptoms of influenza occur?

Symptoms usually start 1 to 3 days after coming into contact with an individual who is ill with influenza.

How is influenza diagnosed?

Usually a doctor will diagnose a case of influenza based on the typical symptoms of fever, headache, sore throat, body aches, and cough. Specific laboratory tests to confirm influenza are available, but they are costly and take many days to process. By that time, the patient is usually well on the way to recovery.

What is the treatment for influenza?

Rest and liquids are usually adequate.  Antiviral drugs may be used to try to reduce the severity of symptoms of influenza A and are effective only if given early in the illness.  Four licensed influenza antiviral agents are available in the United States:  amantadine, rimantadine, zanamivir, and oseltamivir.  Influenza A virus can become resistant to amantadine and rimantadine.  Oseltamivir or zanamivir can be prescribed if antiviral treatment of influenza is indicated.  Oseltamivir is approved for the treatment of people age one year or older and zanamivir is approved for the treatment of people age 7 or older. 

These antiviral drugs are not effective against influenza B.

When, and for how long, is an infected person able to spread influenza?

The "contagious" period varies, but it probably begins the day before symptoms appear and extends for about one week after the first symptoms appeared.

Should an infected person be excluded from work or school?

Because influenza is spread from person to person through the air, individuals who have an influenza-like illness should remain home until they have recovered from their illness.

How can influenza be prevented?

Routine immunization against influenza is the most important control measure.  The influenza vaccine (flu shot) is available through your personal physician, and through a variety of other health care providers, including many local health departments, visiting nurse association, and senior citizen centers. 

Antiviral drugs may be used among certain people to try to prevent infection with influenza A.  Four licensed influenza antiviral agents are available in the United States:  amantadine, rimantadine, zanamivir, and oseltamivir.  Influenza A virus can become resistant to amantadine and rimantadine.  Oseltamivir is the currently the recommended antiviral drug for preventing influenza.

What is the influenza vaccine?

The influenza vaccine is a killed virus vaccine containing three strains of influenza virus, two of Influenza A, and one of Influenza B. The strain components are changed annually based upon worldwide surveillance of circulating influenza strains.

When should I get the influenza vaccine?

October and November are the best times to get immunized, but getting the vaccine up through March can also offer protection. It takes about 2 weeks for the vaccine to stimulate immunity in the body and provide protection so it is best to get vaccinated early.

Are there any side effects to the influenza vaccine?

Most individuals will experience no side effects from the injected influenza vaccine. Less than one-third of those who receive the vaccine will have some soreness at the vaccination site, and about 5% to 10% will experience a headache or a mild fever. The most serious side effect that can occur after an influenza vaccination is an allergic reaction in individuals who have a severe allergy to eggs. For that reason, people who have an allergy to eggs should not receive the influenza vaccine.

Who should get the influenza vaccine?

All people at risk for medical complications from influenza or more likely to require medical care and all people who live with or care for people at high risk for influenza-related complications should receive influenza vaccine annually.  Approximately 73% of the United States population is included in one or more of these target groups.  However, it is estimated that only one third of the United States population received an influenza vaccination in 2006-2007. 

Vaccination is recommended for the following people who are at increased risk for severe complications from influenza, or at higher risk for influenza-associated visits to clinics, emergency departments, or hospitalizations:

• All children aged 6-59 months (i.e., 6 months – 4 years)
• All persons aged 50 or older
• Children and adolescents (aged 6 months – 18 years) who are receiving long-term aspirin therapy and who therefore might be at risk for experiencing Reye syndrome after influenza virus infection
• Women who will be pregnant during the influenza season
• Adults and children who have chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, hematological or metabolic disorders (including diabetes mellitus)
• Adults and children who have weak immune systems
• Adults and children who have any condition that can affect respiratory function or the handling of respiratory secretions or that can increase the risk for aspiration
• Residents of nursing homes and other chronic-care facilities

Persons who live with or care for people at high risk for influenza-related complications is recommended including:

• Health care providers
• Healthy household contacts (including children) and caregivers aged less than 5 years and adults aged 50 or older
• Healthy household contacts (including children) and caregivers of persons with medical conditions that put them at higher risk for sever complications from influenza

Generally no. Because the influenza virus can change its surface markers to elude the body's immune system, individuals who have had an influenza illness or the influenza vaccine in a previous year may still become infected with a new strain. Because of this, the influenza vaccine should be given each year.

Are there any alternatives to getting a shot for preventing influenza?

A new type of influenza vaccine is now available and is sprayed into the nostrils rather than injected into the muscle. This is called an intranasal influenza vaccine. The vaccine, called FluMist™, was licensed in 2003 and is an attenuated (weakened) live vaccine.

Who can get FluMist™?

Live, intranasal influenza vaccine is approved for healthy children and adults from 5 through 49 years of age, including household contacts of some people at high risk for influenza complications. However, because FluMist’s™ safety has not yet been studied in some other high risk groups, it should not be used by individuals in these groups. Check with your doctor to see if the intranasal vaccine is right for you.

Who should not get FluMist™?

The following people should not get intranasal influenza vaccine. Anyone in these groups should contact their health care provider about getting inactivated influenza vaccine.

• Adults 50 years of age or older.
  
• Children younger than 5.
  
• People with long-term health problems such as:
  • Heart disease
  • Lung disease
  • Asthma
  • Kidney disease
  • Metabolic disease such as diabetes
  • Anemia and other blood disorders
    
• People with a weakened immune system due to:
  • HIV/AIDS or another disease that affects the immune system
  • Long-term care with drugs that weaken the immune system such as steroids
  • Cancer treatment with X-rays or drugs
    
• Children or adolescents on long-term aspirin treatment (these people could develop Reye syndrome if they catch influenza).
  
• Pregnant women.
  
• Anyone with a history of Guillain-Barre Syndrome.

The flu shot (inactivated vaccine) is preferred over live, intranasal influenza vaccine for physicians, nurses, family members, or anyone else coming in close contact with anyone with a weakened immune system.

The following people should talk with a doctor before getting either flu vaccine:

• Anyone who has ever had a serious allergic reaction to eggs or to a previous dose of influenza vaccine.
  
• If you have a fever or are severely ill at the time the vaccination is scheduled, you should probably wait until you recover before getting influenza vaccine. Talk to your doctor or nurse about whether to reschedule the vaccination.

What are the risks from live, intranasal influenza vaccine?

A vaccine, like any medicine, is capable of causing serious problems, such as severe allergic reactions. The risk of a vaccine causing serious harm, or death, is extremely small.

Live, intranasal influenza vaccine can cause mild symptoms (see below).

Mild problems:

Some children and adolescents 5-17 years of age reported mild reactions during clinical studies, including:

• Runny nose or nasal congestion
• Fever
• Headaches and muscle aches
• Abdominal pain or occasional vomiting

These problems usually occurred after the first dose and went away on their own.

Some adults 18-49 years of age reported:

• Runny nose or nasal congestion
• Cough, chills, tiredness/weakness
• Sore throat
• Headache

During clinical studies with live, intranasal influenza vaccine, many of these symptoms occurred whether or not the person was vaccinated. Even when they occurred after vaccination, they may not have been caused by the vaccine.

Severe problems:

• Life-threatening allergic reactions are very rare. If they do occur, it would be within a few minutes to a few hours after the vaccination.
  
• No life-threatening reactions were reported during clinical trials of live, intranasal influenza vaccine. However, rare reactions may not be identified until thousands or millions of people have used any new product. Monitoring for unusual or severe problems is being done.

What if there is a moderate or severe reaction?

What should I look for?

• Any unusual condition, such as a high fever or behavior changes. Signs of a serious allergic reaction can include difficulty breathing, hoarseness or wheezing, hives, paleness, weakness, a fast heartbeat or dizziness.

What should I do?

• Call a doctor, or get the person to a doctor right away.
  
• Tell the doctor what happened, the date and time it happened, and when the vaccination was given.
  
• Ask the doctor, nurse, or health department to report the reaction by filing a Vaccine Adverse Event Reporting System (VAERS) form. Or call VAERS at 1-800-822-7967, or visit www.vaers.org.