How to Prevent the Flu

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Influenza cannot be prevented in all cases. To help prevent the flu, avoid close contact with people who are sick.

Wash your hands frequently and avoid touching your eyes, nose, and mouth. Cover your mouth and nose with a tissue when coughing or sneezing.

Some research shows that wearing a flu mask may also help prevent airborne transmission of influenza viruses and reduce the spread of germs from your hands to your mouth and nose.

However, the best way to prevent the flu is to receive a flu vaccine each year, usually in the fall. There are two types of vaccines available to help prevent the flu: the flu shot and the nasal-spray flu vaccine.

Types of Flu Vaccines

The flu shot is an inactivated vaccine (i.e., it contains killed viruses) that is usually administered as a shot in the upper arm. The flu shot is approved for use in people over 6 months of age. It can be given to healthy people as well as people who have chronic medical conditions and are at increased risk for developing complications from the flu.

In January 2013, the U.S. Food and Drug Administration (FDA) approved the first seasonal flu vaccine manufactured using a new technology. This vaccine, called Flublok, is approved for use in people between the ages of 18 and 50. Flublok is produced using insect virus (baculovirus) expression technology instead of the influenza virus or eggs, which are used in the production of other previously-approved flu vaccines. Side effects are similar to other flu shots.

The first flu vaccine to contain an added substance that enhances the body's immune response to an antigen (called an adjuvant) was approved by the FDA in November 2015. This seasonal flu vaccine is approved for use in people 65 and over. The substance—called MF59—is a highly purified form of squalene oil, which occurs naturally in humans, as well as in shark-liver oil, and some vegetable oils. In clinical trials, no safety concerns were identified. Side effects were the same as for other flu vaccines (e.g., pain and tenderness at the site of the injection, muscle aches, etc.)

Antibodies to protect against influenza viruses develop in the body about 2 weeks after vaccination. Each flu vaccine contains 3 or 4 different flu viruses, based on scientific estimates about which types and strains of flu will circulate in the upcoming flu season. However, flu viruses are continually mutating—mutations are called "drift"—and vaccines, which are formulated months in advance, don't always protect well against drifted viruses. The Centers for Disease Control and Prevention (CDC) continues to recommend flu vaccines for everyone 6 months of age and older because immunization is thought to provide at least "cross-protection," which reduces the risk for serious side effects from the flu.

The flu vaccine is not used in children younger than 6 months of age. To help reduce the risk for flu in children who are too young to be immunized, some health care providers recommend that family members, caregivers, and others who have regular contact with infants should receive the flu vaccine.

The nasal-spray flu vaccine (e.g., FluMist), which is sometimes called LAIV (Live Attenuated Influenza Vaccine), is made with live, weakened flu viruses. This vaccine is approved for use in healthy people aged 5–49 who are not pregnant. In September 2007, the FDA expanded approval for FluMist to include children 2–5 years of age.

Flu Vaccine Side Effects

Side effects of the flu shot include soreness, redness, and swelling at the site of the injection; low-grade fever; and muscle aches. These side effects usually last 1 or 2 days. Rarely, the flu vaccine can cause severe allergic reactions.

The nasal-spray flu vaccine also may cause side effects (e.g., runny nose, headache). In children, side effects can include vomiting, muscle aches, and fever, and in adults, it can also cause cough and sore throat.

Antiviral Medications

Antiviral medications may be used to help prevent the flu in patients who are at high risk for complications (e.g., people 65 years of age and older, children between 12 and 23 months of age, and people who have chronic medical conditions). Antivirals approved by the Food and Drug Administration to prevent influenza A infection include amantadine (Symmetrel), rimantadine (Flumadine), and oseltamivir (Tamiflu). Oseltamivir and zanamivir (Relenza) also are effective against influenza B viruses.

In healthy adults, antiviral drugs can prevent influenza infection in about 70–90 percent of cases. They often are prescribed to control flu outbreaks in places where people at high risk for complications are in close contact with one another (e.g., nursing home, hospital).

Side effects of antiviral medications include the following:

  • Anxiety
  • Difficulty concentrating
  • Insomnia
  • Lightheadedness
  • Loss of appetite
  • Nausea and vomiting
  • Nervousness

Updated by Remedy Health Media

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 01 Aug 2007

Last Modified: 01 Dec 2015