Influenza and Vaccine

WHAT IS INFLUENZA?

Influenza ("flu") is a viral infection of the respiratory tract (nose, throat, bronchial tubes, and lungs).  The virus usually spreads through the air, especially in crowded spaces, or may be transmitted by direct contact.  Flu symptoms usually appear 1-3 days after exposure which may include fever, chills, headache, generalized muscle aches, sore throat, cough, and intestinal symptoms.  Although most people are ill for only a few days, more serious cases may require hospitalization.  In the U.S., influenza usually occurs from November to April and is associated with thousands of deaths, especially in older people.

WHAT IS SEASONAL INFLUENZA VACCINE?

Seasonal influenza vaccine is a sterile solution of inactivated virus, given intramuscularly, that produces specific antibodies.  This year's flu vaccine is specific to the types of flu which are likely to occur in the U.S. this winter season.  Protection from the vaccine will begin around 1-2 weeks after the shots, but immunity may decrease after several months.  Also, the viruses that cause flu frequently change; therefore, vaccination is recommended every year.  The optimal time to vaccinate is October to mid November, since in the U.S., influenza generally peaks between December and early March.  Flu shots will not protect all persons from the flu, nor will they protect against all strains of flu or illness caused by other viruses.

WHO SHOULD GET SEASONAL INFLUENZA VACCINE?

The following groups are at the highest risk for serious illness from the flu and for whom the vaccine is recommended:

• All people over 65 years of age.
• Residents of nursing homes or other institutions housing patients of any age with chronic medical conditions.
• Adults and children with long-term heart or lung problems, including children with asthma.
• Persons with chronic disorders that require regular medical follow-ups or hospitalizations.
• Persons who have an immunological disorder (or use medications) that lowers the body's normal resistance to influenza, including those infected with HIV/AIDS.
• Women who will be in the second or third trimester of pregnancy during the flu season.

The following groups are capable of transmitting influenza to high-risk persons and, therefore, the vaccine is recommended:

• Personnel in hospitals and outpatient settings.
• Providers of home care or household members caring for high-risk persons.

The seasonal flu vaccine may be given to anyone wishing to reduce their chances of catching the flu, including students or personnel in schools and foreign travelers if indicated.

POSSIBLE SIDE EFFECTS:

• Local tenderness at the injection site (10-64%, lasting up to two days).  These local reactions generally are mild and rarely interfere with the persons ability to conduct usual daily activities.
• Generalized reactions such as fever, malaise, muscle soreness.
• Rarely, allergic reactions such as hives, swelling, or anaphylaxis.

This vaccine cannot cause influenza.  Respiratory disease after the vaccine is coincidental and unrelated to the vaccine.

CONTRAINDICATIONS:

• Known hypersensitivity to eggs or egg products or other components of the vaccine.
• Known hypersensitivity to thimerosal (a preservative found in some vaccines and some contact lens solutions).
• Moderate to severe illness, with or without fever; or an active neurological disorder.
• Those with past history of Guillain-Barre syndrome.
• Those with known sensitivity to dry natural rubber latex.
• Those with allergy to streptomycin (Parkedale vaccine only)

PRECAUTIONS:

• Bleeding disorders.
• Pregnancy.
• Immunosuppressive persons may not respond optimally to the vaccine.
• Those taking the medications Theophylline or Warfarin, Phenytoin or Aminopyrine.

PREGNANCY AND INFLUENZA VACCINE:

The Advisory Committee on Immunization Practices (ACIP) recommends that women who will be beyond the first trimester of pregnancy (14 weeks of gestation) during the influenza season be vaccinated.  Pregnant women who have medical conditions that increase their risk for complications from influenza should be vaccinated before the season, regardless of stage of pregnancy.  Studies of influenza immunizations of more than 2,000 pregnant women have demonstrated no adverse fetal effects associated with influenza vaccine.  However, animal reproduction studies have not been conducted with influenza virus vaccine.  It is also not known whether influenza virus vaccine can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity.  The benefits of preventing influenza-related complications versus the theoretical risk of fetal harm should be considered.  We require that you discuss this with your physician before receiving influenza vaccine.

Questions or side effect reporting: Call Olin Health Center, Allergy & Immunization Clinic at 353-9763 or MSU Occupational Health.

Sources:  Travel & Routine Immunizations, 1999.
Manufacturers vaccine inserts, 1998.

For more information go to the Olin Colds & Flu page.