Influenza Prevention: Information for Travelers

a family with their child ready to board a plane

Get more information on influenza for travelers from CDC’s publication Health Information for International Travel (commonly called the Yellow Book).

In the Northern Hemisphere, the flu season can begin as early as October and can last as late as April or May.
In the temperate regions of the Southern Hemisphere, influenza activity typically occurs during April – September.
In the tropics, influenza activity occurs throughout the year.
Travelers in the Northern and Southern Hemispheres can be exposed to influenza during months that fall outside of those listed above, especially when traveling as part of large tourist groups (e.g., on cruise ships) that include people from areas of the world where influenza viruses are circulating.

CDC recommends that everyone 6 months and older get a flu vaccine yearly.

Everyone 6 months and older should get a flu vaccine yearly, preferably in the fall before the U.S. flu season begins.

People who have not gotten a flu vaccine for the current season and are traveling to parts of the world where influenza activity is ongoing should get a flu vaccine to protect themselves during their trip.

This is particularly important for people at high risk of flu-related complications.
The flu vaccine used in the Northern Hemisphere usually protects against the main viruses that have been circulating in other parts of the world.

People should get vaccinated at least 2 weeks before travel because it takes 2 weeks for vaccine immunity to develop after vaccination.

No information is available about the benefits of getting revaccinated before summer travel for those people who already were vaccinated during the preceding fall, so revaccination is not recommended.
Keep in mind that influenza vaccine manufactured for the upcoming or current season usually expires the following June. After June, flu vaccines are usually not available in the U.S. until the influenza vaccine for the next season is produced and made available in the fall.
Also, even if you receive the previous season’s vaccine before travel during the summer months, you should still receive the new flu vaccine that coming fall or winter.

More Information for Travelers

If you are sick with symptoms of influenza-like illness, you should not travel. These symptoms include fever, cough, sore throat, runny or stuffy nose, muscle or body aches, headache, and fatigue. Some people may have vomiting and diarrhea, though this is more common in children than adults. It’s important to note that not everyone with flu will have a fever.
If you are sick, stay home until at least 24 hours after you no longer have a fever* or signs of a fever without the use of a fever-reducing medicine, such as Tylenol®.

Travel Preparation

Investigate current flu activity in your region of travel. The Centers for Disease Control and Prevention provide frequently updated information on seasonal flu activity throughout the world.
Additional Travel Resources:
- CDC: Travelers’ Health Website (General)
- CDC: Traveler Information Center

During and After Your Trip

During your trip, follow local guidelines and practice healthy habits

Pay attention to announcements from the local government in your travel destination and monitor the local health and security situation.
Follow any movement restrictions and prevention recommendations.
Wash your hands often with soap and running water, especially after coughing or sneezing. (Use alcohol-based hand sanitizer — containing at least 60% alcohol1,2 — when soap is not available and hands are not visibly dirty.)
Cover your mouth and nose with a tissue when you cough or sneeze, and put the used tissue in the trash. If you don’t have a tissue, cough or sneeze into your upper sleeve, not your hands.
Avoid close contact with sick people.

What to do if you feel sick

It is expected that most people infected with flu will recover without needing medical care. However, if you have severe illness or you are at high risk for flu complications, seek medical care.

A U.S. consular officer can help you find local medical care in a foreign country. To contact the U.S. embassy or consulate in the country you are visiting, call Overseas Citizens Services at: 1-888-407-4747 if calling from the U.S. or Canada, 00-1-202-501-4444 if calling from other countries. You can also visit the websites of U.S. Embassies, Consulates, and Diplomatic Missions to find the contact information for the local U.S. Embassy of the country you are visiting.

Follow all local health recommendations.

Tips for After Your Trip

Closely monitor your health for 7 days. If you become ill with flu symptoms, seek medical attention if they are severe.

Kampf G, Kramer A. Epidemiologic background of hand hygiene and evaluation of the most important agents for scrubs and rubs.external icon Clin Microbiol Rev. 2004 Oct;17(4):863-93.
Todd EC, Michaels BS, Holah J, Smith D, Greig JD, Bartleson CA. Outbreaks where food workers have been implicated in the spread of foodborne disease. Part 10. Alcohol-based antiseptics for hand disinfection and a comparison of their effectiveness with soaps.external icon J Food Prot. 2010 Nov;73(11):2128-40.

Footnote

*Many authorities use either 100 (37.8 degrees Celcius) or 100.4 F (38.0 degrees Celsius) as a cut-off for fever, but this number actually can range depending on factors such as the method of measurement and the age of the person, so other values for fever could be appropriate. CDC has public health recommendations that are based on the presence (or absence) of fever. What is meant by this is that the person’s temperature is not elevated beyond their norm.