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CDC-INFO Inquiries and Responses

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Who should not get an influenza (flu) shot?

Talk to your doctor before getting an influenza (flu) shot if you:

  • Have ever had a severe allergic reaction to eggs;
  • Have ever had a severe allergic reaction to a flu shot before; or
  • Have ever gotten Guillain-Barré syndrome (GBS) after receiving the flu vaccine.

Also, flu vaccine is not approved for use for children younger than 6 months of age. If you have a fever when you go to get your flu shot, talk to your doctor about getting your shot at a later date. But, if you have a respiratory (breathing) illness (e.g., cough, cold) without a fever, or other mild illness, you can get a flu shot. If you have questions about whether you should get a flu shot, talk to your doctor.

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Can the influenza (flu) vaccine give me the flu?

Neither the influenza (flu) shot nor the nasal-spray flu vaccine (live attenuated influenza vaccine or LAIV) can give you the flu. The 3 flu viruses used in the flu shot are inactivated (killed); meaning they can't cause infection. The nasal spray vaccine does use live viruses, but they're weakened and can't cause the flu.

After getting the flu vaccine, some people still get sick with flu-like symptoms. This may be because they:

  • Were exposed to the flu virus just before they got vaccinated, or before the vaccine had time to work, and actually got the flu;
  • Got infected by another kind of virus that causes the same symptoms as flu; or
  • Got infected by a strain of flu virus that wasn't included in the vaccine.

Call to Action

CDC recommends that everyone 6 months of age and older get the flu vaccine each year. It's the first and most important step in protecting yourself and your loved ones from flu viruses.

The 2012-2013 flu vaccine includes an influenza A (H1N1) virus, an influenza A (H3N2) virus and an influenza B virus.

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What side effects can occur after getting an inactivated influenza (flu) vaccine (shot)?

Possible side effects that can occur after getting an inactivated influenza (flu) vaccine (shot) include:

  • Soreness, redness, or swelling where the shot was given;
  • A low-grade fever; and
  • Aches.

If these problems do occur, they usually begin soon after the shot is given and last 1 to 2 days.

Call to Action

CDC recommends that everyone 6 months of age and older get the flu vaccine each year. It's the first and most important step in protecting yourself and your loved ones from flu viruses.

The 2012-2013 flu vaccine includes an influenza A (H1N1) virus, an influenza A (H3N2) virus and an influenza B virus.

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If a person has been sick with influenza (flu), should he or she still receive the flu vaccine during that same season?

You should still get the influenza (flu) vaccine, even if you've already had the flu this season. This is because the vaccine protects against 3 strains of influenza. Even if you had the flu, you may have been infected by only 1 of the strains in the vaccine. If you don't get the vaccine, you're still at risk of getting sick from the other 2 strains.

Call to Action

CDC recommends that everyone 6 months of age and older get the flu vaccine each year. It's the first and most important step in protecting yourself and your loved ones from flu viruses.

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How long is a person with influenza (flu) contagious?

Most healthy adults are contagious (able to spread) with influenza (flu) from 1 day before getting sick to 5 to 7 days after the onset of symptoms. The amount of time someone is contagious with the flu depends on their age and overall health. Some young children and people with weakened immune (body defense) systems may be contagious for longer than a week.

If you're sick with flu-like illness, CDC recommends that you stay home for at least 24 hours after your fever is gone except to get medical care or for other necessities. Your fever should be gone without the use of a fever-reducing medicine. You should also keep away from others as much as possible to keep from infecting them and making them sick. A person is most contagious during the time that they have a fever.

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When should I get the influenza (flu) vaccine?

CDC recommends that people get the 2012–2013 flu vaccine as soon as it becomes available. You can get it any time during the flu season, into January and beyond. The timing and length of the flu season varies. Flu outbreaks can happen as early as October, but flu activity often peaks in January or February and can last as late as May.

It takes about 2 weeks after vaccination for antibodies to develop in the body and provide protection against influenza virus infection. Therefore, CDC recommends that vaccination efforts begin as soon as vaccine becomes available to ensure that as many people as possible are protected before flu season begins.

Some children 6 months through 8 years of age may need two doses of vaccine to be fully protected against influenza.

If a child needs 2 doses, it's best to begin vaccination early so the child is protected for as much of the flu season as possible. The first dose would ideally be given as soon as the vaccine is available. The second dose should be given at least 28 days (4 weeks) after the first dose.

Providers should continue to offer the vaccine throughout the flu season and as long as flu is still circulating.

Call to Action

CDC recommends that everyone 6 months of age and older get the flu vaccine each year. It's the first and most important step in protecting yourself and your loved ones from flu viruses.

The 2012-2013 flu vaccine includes an influenza A (H1N1) virus, an influenza A (H3N2) virus and an influenza B virus.

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What vaccines should I get before traveling to a destination where malaria IS present, but yellow fever is NOT?

CDC Resources

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What is the role of CDC-INFO?

The role of CDC-INFO is to provide reliable, consistent, science-based health information on behalf of the Centers for Disease Control and Prevention (CDC). CDC-INFO is not a part of CDC. However, the CDC has reviewed and authorized all of the information that CDC-INFO provides.

CDC-INFO also provides referrals to:

  • local health departments,
  • clinics, and
  • testing sites in your area.

CDC-INFO is not a consumer advocacy group. It does not enforce product safety or protect consumers' rights.

CDC-INFO does NOT provide:

  • counseling,
  • diagnoses, or
  • personal medical advice.

Please see your own doctor for these needs.

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How soon should I get tested if I think I have been exposed to HIV?

Most people develop antibodies to HIV within 2 to 8 weeks after exposure. The average is 25 days. Ninety-seven (97) percent of people develop antibodies within the first 3 months after infection. In rare cases, it can take up to 6 months. Antibodies are chemicals produced by the body's immune (defense) system to fight infection. HIV antibody tests measure antibodies to HIV. But, it can take time for the body to produce enough antibodies for an HIV antibody test to detect.

Therefore, if you have an HIV antibody test within 3 months of possible exposure and the result is negative, you should repeat the test at least 3 months after your last potential exposure.

Another type of test, called an RNA test, detects the HIV virus directly. These tests can detect HIV 9 to 11 days after infection. These tests are more costly and used less often than antibody tests.

Call to Action

CDC would like to remind you that you can spread HIV to others as soon as you get the virus. This is true even if you don't have symptoms and don't know you're infected.

If you've recently had an HIV test, it's important to avoid having any type of sex while you're waiting to find out your test results. If this isn't an option for you, be sure to practice safer sex to reduce exposure to blood, semen, or vaginal fluids. This will reduce the chance that you'll spread any virus you might have to others.

CDC Resources

External Resources

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Can you help me locate a STD testing site in my area?

CDC Resources

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Can you help me locate an HIV testing site in my area?

Many places offer HIV testing. Common testing locations include:

  • local health departments,
  • private doctors' offices,
  • hospitals, and
  • other sites set up just for HIV testing.

Some sites will test you without you having to give your name. Other sites offer types of tests where your name is used, but information is protected. If this is an important issue for you, ask the site what their policy is.

If you have questions about HIV or AIDS, it's important to be tested at a place that also provides counseling.

Counselors can:

  • Answer any questions you might have about risky behaviors;
  • Tell you about ways you can protect yourself and others in the future;
  • Help you understand the meaning of the test results; and
  • Tell you about HIV- and AIDS-related resources in your area.

If you don't have a doctor, we can help you find testing sites in your area.

You can also:

Call to Action

CDC would like to remind you that you can spread HIV to others as soon as you get the virus. This is true even if you don't have symptoms and don't know you're infected.

If you've recently had an HIV test, it's important to avoid having any type of sex while you're waiting to find out your test results. If this isn't an option for you, be sure to practice safer sex to reduce exposure to blood, semen, or vaginal fluids. This will reduce the chance that you'll spread any virus you might have to others.

CDC Resources

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Is CDC a regulatory agency?

CDC is not a regulatory or enforcement agency and does not make policy decisions. CDC conducts science-based investigations, research, and public health surveillance (tracking) both nationally and internationally when there is an outbreak (large number of cases) of disease. CDC makes recommendations that are used by state and other Federal agencies to make and enforce laws.

The only exception to this is with CDC's National Institute for Occupational Safety and Health (NIOSH). NIOSH's only regulations are those that govern the procedures and requirements for the testing and certification of respirators. But, even the respirator testing and certification program is voluntary.

ALL TIERS: Provide the inquirer with the contact information for his or her state health department, if appropriate, and/or the external resource(s) listed below.

CDC Resources

External Resources

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What are the signs and symptoms of HIV?

The only way to know if you're infected with HIV is to be tested. You can't rely on symptoms to know whether or not you're infected. Many people who are infected with HIV don't have any symptoms at all for 10 years or more.

The following may be warning signs of advanced infection with HIV:

  • Rapid weight loss;
  • Dry cough;
  • Night sweats or fever that keeps coming back;
  • Feeling very tired for no reason;
  • Swollen lymph glands in the armpits, groin, or neck;
  • Diarrhea that lasts for more than a week;
  • White spots on the tongue, in the mouth, or in the throat;
  • Pneumonia (noo-MOH-nee-uh) (lung infection);
  • Red, brown, pink, or purplish spots on or under the skin or inside the mouth, nose, or eyelids; and
  • Memory loss, depression, and other neurological (noor-uh-LOG-ji-kuhl) (brain and spine) problems.

If you have any of these symptoms, don't assume that you're infected with HIV. Each of these symptoms can be related to other illnesses.

Call to Action

The only way to know if you have HIV is to get tested. If you think you may have been exposed to HIV, talk to your doctor. He or she can help you find out if you're infected.

If you don't have a doctor, we can help you find testing sites in your area.

You can also:

CDC Publication

CDC Resources

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How is HIV transmitted from 1 person to another?

HIV can be transmitted (spread) when certain body fluids from an infected person enter the body of an uninfected person.

These fluids include:

  • blood,
  • semen (cum),
  • vaginal fluid, and
  • breast milk.

HIV can enter the body if these fluids:

  • Are directly injected into the blood stream from a needle or syringe;
  • Come in contact with damaged skin, such as a cut or sore; or
  • Come in contact with mucous membranes.

Mucous membranes are soft, moist areas just inside the openings of the body, such as the:

  • mouth,
  • vagina,
  • anus (opening to the rectum),
  • eyes,
  • nose, and
  • urethra (opening at the tip of the penis).

In the U.S., HIV is most often spread through:

  • Specific sexual behaviors, such as anal or vaginal sex; or
  • Sharing needles with an infected person.

It's less common for HIV to be spread:

  • Through oral sex; or
  • From an infected mother to her baby, either before birth, or after birth through breastfeeding or pre-chewing food for her infant.

In the U.S., it's also possible to get HIV through:

  • Exposure to infected blood;
  • Transfusions of infected blood or blood products; and
  • Organ transplants.

But, this risk is very small, due to rigorous testing of the U.S. blood supply and donated organs.

Some healthcare workers have been infected after:

  • Being stuck with needles containing HIV-infected blood; and
  • Having infected blood come in contact with the worker's open cut or splashed into his or her eyes or nose, though this is less common.

There has been only 1 case of a patient being infected by an HIV-infected dentist.

Call to Action

The only way to know if you have HIV is to get tested. If you think you may have been exposed to HIV, talk to your doctor. He or she can help you find out if you're infected.

f you don't have a doctor, we can help you find testing sites in your area.

You can also:

CDC Publication

CDC Resources

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What vaccines should I get before traveling to a destination where BOTH malaria AND yellow fever are present?

CDC Resources

  • Travelers' Health 
    National Center for Emerging and Zoonotic Infectious Diseases, Division of Global Migration and Quarantine
  • Travelers' Health: Vaccinations 
    National Center for Emerging and Zoonotic Infectious Diseases, Division of Global Migration and Quarantine
  • Travelers' Health: Travel Notices 
    National Center for Emerging and Zoonotic Infectious Diseases, Division of Global Migration and Quarantine
  • Your Survival Guide to Safe and Healthy Travel 
    National Center for Emerging and Zoonotic Infectious Diseases, Division of Global Migration and Quarantine
  • Travelers' Health Yellow Book: Chapter 2: The Pre-Travel Consultation: Malaria: Malaria Risk Information and Prophylaxis, By Country
    National Center for Emerging and Zoonotic Infectious Diseases, Division of Global Migration and Quarantine
  • Malaria 
    National Center for Zoonotic, Vector-Borne, and Enteric Diseases, Division of Parasitic Diseases
  • Search for Yellow Fever Vaccination Clinics 
    National Center for Emerging and Zoonotic Infectious Diseases, Division of Global Migration and Quarantine
  • Yellow Fever 
    National Center for Zoonotic, Vector-Borne, and Enteric Diseases, Division of Vector Borne Infectious Diseases

External Resources

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Contact Us:
  • Page last reviewed: May 18, 2011
  • Page last updated: May 18, 2011
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