Understanding the Flu Vaccine

David P. Calfee, MD, infection control officer at Mount Sinai Medical Center, recently discussed the flu vaccine:

Q: What is the seasonal flu shot?

A: The seasonal flu shot is given annually and protects against three common viruses, one influenza A (H3N2) virus, one regular seasonal influenza A (H1N1) virus—not the pandemic 2009 H1N1 virus—and one influenza B virus. It is usually administered by injection, typically in the upper arm. Seasonal flu shots do not protect against the pandemic H1N1 virus, commonly known as the “Swine Flu.”

Q: Why should I get the flu vaccine?

A: The flu vaccine significantly reduces your chance of infection. Each year more than 200,000 people are hospitalized and 36,000 die from the flu, according to the Centers for Disease Control and Prevention (CDC). The elderly, young children, pregnant women, and those with health conditions are at higher risk of developing serious flu-related complications.

Q: Is the pandemic H1N1 virus really a threat this flu season? If so, is there a vaccine?

A: The CDC is predicting that pandemic H1N1 will be a serious threat during the 2009–2010 influenza season. An H1N1 vaccine has been recently developed and will be available this fall. The H1N1 vaccine will be used in addition, and not as a substitute, to the seasonal flu vaccine. The CDC recommends that pregnant women, caretakers of children younger than 6 months, health care and emergency medical services personnel, persons 6 months to 24 years of age, and those people between the ages of 25 and 64 who are at higher risk for H1N1 infection because of chronic health disorders or compromised immune systems, be given priority to receive the H1N1 vaccine. The H1N1 vaccine will be made available to others once sufficient amounts of the vaccine are available.

Q: Do these vaccines have side effects?

A: Influenza vaccines are very safe. Mild side effects like soreness, redness or swelling at the injection site, low-grade fever, or muscle aches may occur.

Q: Is there anyone who should not receive the flu shot?

A: You should not receive the flu shot if you have ever experienced a severe allergic reaction—known as anaphylaxis—to a previous influenza vaccine, eggs, or any other component of the flu shot, or if you have a history of Guillain-Barré syndrome within six weeks of a prior influenza vaccine. If you have a fever or other moderate or severe acute illness, discuss with your doctor if you should postpone your flu shot until that illness resolves.

Q: Should healthcare workers receive the flu and H1N1 vaccines?

A: Yes. Healthcare workers may be at increased risk of influenza infection. Infected healthcare workers can transmit the infection to others, including their family, friends, colleagues, and patients. Vaccination can reduce all of these risks.

 The New York State Department of Health has recently mandated that healthcare personnel in hospitals and many other healthcare settings receive the flu shot each year. This year, both the seasonal influenza and H1N1 influenza vaccines will be required.