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Occupational Exposure to HIV: Information for Health-care Workers 

Frequently Asked Questions

June 29, 1999

Frequently asked questions:

General Information on Occupational Exposures to HIV


Health-care workers are at risk for occupational exposure to the human immunodeficiency virus (HIV). Exposures occur through needlesticks or cuts from other sharp instruments (percutaneous exposures) contaminated with an infected patient's blood or through contact of the eye, nose, or mouth (mucous membrane) or skin with a patient's blood.

Most exposures do not result in infection. The risk of infection varies with the type of exposure and factors such as:

  • The amount of blood involved in the exposure
  • The amount of virus in the patient's blood at the time of exposure
  • Whether postexposure treatment was taken.

Your employer should have in place a system for reporting exposures in order to quickly evaluate the risk of infection from the exposure, counsel you about recommendations for treatments available to prevent infection, and monitor you for side effects of treatments and determine if infection occurs. This may involve testing your blood and that of the source patient and offering appropriate postexposure treatment.

How can occupational exposures be prevented?

Many needlesticks and other cuts can be prevented by using medical devices with safety features designed to prevent injuries by using safer techniques (e.g., not recapping needles by hand), and by disposing of used needles in appropriate sharps disposal containers. Many exposures to the eyes, nose, mouth, or skin can be prevented by using appropriate barriers (e.g., gloves, eye and face protection, gowns) when contact with blood is expected.

If an Exposure Occurs

What should I do if I am exposed to the blood of a patient?

  1. Immediately following an exposure to blood:

    • Needlesticks and cuts should be washed with soap and water.
    • Splashes to the nose, mouth, or skin should be flushed with water.
    • Eyes should be irrigated with clean water, saline, or sterile irrigants.

    No scientific evidence shows that the use of antiseptics for wound care or squeezing the wound will reduce the risk of transmission of HIV. The use of a caustic agent such as bleach is not recommended.

  2. Following any blood exposure you should:

    • Report the exposure to the department (e.g., occupational health, infection control) responsible for managing exposures. Prompt reporting is essential because, in some cases, HIV postexposure treatment may be recommended and it should be started as soon as possible -- preferably within 1-2 hours.
    • In addition to HIV, discuss the possible risks of acquiring hepatitis B and hepatitis C with your health-care provider. You should have already received hepatitis B vaccine, which is extremely safe and effective in preventing hepatitis B.

Risk of Infection after Exposure

What is the risk of HIV infection after an occupational exposure?

While the risk is very low, it is not zero. HIV infection has been reported after occupational exposures to HIV-infected blood through needlesticks or cuts; splashes in the eyes, nose, or mouth; and skin contact.

  • Exposures from needlesticks or cuts cause most infections. The average risk of HIV infection after a needlestick/cut exposure to HIV-infected blood is 0.3% (i.e., three-tenths of one percent, or about 1 in 300). Stated another way, 99.7% of needlestick/cut exposures do not lead to infection.
  • The risk after exposure of the eye, nose, or mouth to HIV-infected blood is estimated to be, on average, 0.1% (1 in 1,000).
  • The risk after exposure of the skin to HIV-infected blood is estimated to be less than 0.1%. A small amount of blood on intact skin probably poses no risk at all. There have been no cases of HIV transmission documented due to an exposure involving a small amount of blood on intact skin. The risk may be higher if the skin is damaged (e.g., by a recent cut) or if the contact involves a large area of skin or is prolonged.

Risk from all exposures is probably increased if the exposure involves a larger volume of blood or a higher amount of HIV in the patient's blood. (Source-patients near death with AIDS or patients with symptoms of acute HIV infection usually have higher amounts of HIV in their blood.)

How many health-care workers have been infected with HIV occupationally and under what circumstances?

As of December 1996, CDC had received reports of 52 documented cases and 111 possible cases of occupationally acquired HIV infection among health-care workers in the United States.

Health-Care Workers with Documented
Occupationally Acquired HIV Infection
Type of occupational exposureNumber
Needlestick or cuts45
Eye, nose, or mouth, and/or skin5
Both injury & mucous membrane1
Type of fluid involved in exposure Number
Concentrated virus in a laboratory3
Visibly bloody fluid1
Unspecified fluid1

The 111 possible cases were in health-care workers who reported an occupational exposure to blood, body fluids, or HIV-infected laboratory material, and who did not have any other identifiable behavioral or transfusion risk for HIV infection. However, for these workers, infection specifically resulting from an occupational exposure was not documented.

Treatment for the Exposure

Is treatment available after an occupational exposure to HIV?

Yes. Results from a small number of studies suggest that the use of zidovudine (ZDV) and other antiviral drugs after certain occupational exposures may reduce the chance of HIV transmission. In one study the use of ZDV after HIV exposure from a needlestick or cut reduced the risk of HIV infection by almost 80%.

Will treatment after exposure prevent HIV infection?

These studies suggest that postexposure treatment may prevent infection with HIV. However, because there have been at least 12 reported cases of ZDV failing to prevent HIV infection in health-care workers, postexposure treatment will probably not prevent all cases of infection transmission.

Is postexposure treatment recommended for all types of occupational exposures to HIV?

No. Because most occupational exposures do not lead to HIV infection, the chance of possible serious side effects (toxicity) from the drugs used to prevent infection may be much greater than the chance of HIV infection from such exposures. Both risk of infection and possible side effects of drugs should be carefully considered when deciding whether to take postexposure treatment. Exposures with a lower infection risk may not be worth the risk of the side effects associated with these drugs.

What about exposures to blood for which the HIV status of the source person is unknown?

If the source individual cannot be identified or tested, decisions regarding follow-up should be based on the exposure risk and whether the source is likely to be a person who is HIV positive. Follow-up HIV testing should be available to all workers who are concerned about possible HIV infection through occupational exposure.

Treatments Available

What specific drugs are recommended for postexposure treatment?

In June 1996, the Public Health Service recommended that zidovudine (ZDV), lamivudine (3TC), and a protease inhibitor, preferably indinavir (IDV), be used as follows:

  • ZDV should be considered for treatment of all exposures involving HIV-infected blood, fluid containing visible blood, or other potentially infectious fluid or tissue.
  • 3TC should be added to ZDV for increased effectiveness and for use against ZDV-resistant types of virus. Used in combination, ZDV and 3TC are very effective in treating HIV infection, and considerable information shows that they are safe when used for a short time.
  • IDV should be added for the highest risk exposures, such as those involving a larger volume of blood with a larger amount of HIV. IDV is a potent antiviral drug that appears to be safe when taken for a short period, although less information is available about the safety of this drug.

Since June 1996, several new antiviral drugs have been licensed for use in the United States. The Public Health Service recommendations will be reviewed and may be modified in 1997, taking into account the availability of these additional drugs.

Can other antiviral drugs be used or substituted if these drugs are not available?

These recommendations are intended to provide guidance to clinicians and may be modified on a case-by-case basis. Whenever possible, consulting an expert with experience in the use of antiviral drugs is advised, especially if a recommended drug is not available, if the source patient's virus is likely to be resistant to one or more recommended drugs, or if the drugs are poorly tolerated.

Should zidovudine ever be used alone?

ZDV alone may be considered for some lower risk exposures when the virus is likely to be sensitive to the drug.

How soon after exposure to HIV should treatment start?

Treatment should be started promptly, preferably within 1-2 hours, after the exposure. Although animal studies suggest that treatment is not effective when started more than 24-36 hours after exposure, it is not known if this time frame is the same for humans. Starting treatment after a longer period (for example, 1-2 weeks) may be considered for the highest risk exposures; even if HIV infection is not prevented, early treatment of initial HIV infection may lessen the severity of symptoms and delay the onset of AIDS.

How long do the drugs need to be taken?

The optimal course of treatment is unknown; because 4 weeks of ZDV appears to provide protection against HIV infection, if tolerated, treatment should probably be taken for 4 weeks.

Has the FDA approved these drugs to prevent HIV following an occupational exposure?

No. The FDA has approved these drugs for the treatment of HIV infection, but not for preventing infection. However, physicians may prescribe any approved drug when, in their professional judgement, the use of the drug is warranted.

Safety and Side Effects

What is known about the safety and side effects of these drugs?

Most of the information known about the safety and side effects of these drugs is based on studies of their use in HIV-infected individuals. For these individuals, ZDV and 3TC have usually been well tolerated when taken in the doses recommended. There is less information about IDV, but it also may be well tolerated when used for a short period. IDV should not be used in combination with certain other drugs, including some prescription antihistamines (consult your health-care provider). Some of the more frequent side effects reported in HIV-infected patients include the following:

  • Upset stomach (for example, nausea, vomiting, diarrhea), tiredness, or headache for people taking ZDV
  • Upset stomach and, in rare instances, pancreatitis for people taking 3TC
  • Jaundice and kidney stones in people taking IDV, although these side effects are infrequent when IDV is taken for less than one month. The risk of kidney stones may be reduced by drinking 48 oz of fluid per 24-hour period.

There is some information about ZDV use by health-care workers as postexposure treatment. ZDV is usually tolerated, but reported side effects have included upset stomach, tiredness, and headache, all of which stopped when the drug was stopped. There is little information on the side effects of 3TC or IDV in uninfected individuals.

Should pregnant health-care workers take these drugs?

Based on limited information, ZDV taken in the second and third trimesters of pregnancy has not caused serious side effects in mothers or infants. There is very little information on the safety of ZDV when taken during the first trimester or on the safety of other antiviral drugs taken during pregnancy. If you are pregnant at the time you have an occupational exposure to HIV, you should consult a physician about the use of antiviral drugs for postexposure treatment.

Follow-Up After the Exposure

What follow-up should be done after an exposure?

  • You should be tested for HIV antibody as soon as possible after exposure (baseline), and periodically for at least 6 months after the exposure (e.g., at 6 weeks, 12 weeks, and 6 months).
  • If you take antiviral drugs for postexposure treatment, you should be checked for drug toxicity, including a complete blood count and kidney and liver function tests just before starting treatment and 2 weeks after starting treatment.
  • You should report any sudden or severe flu-like illness that occurs during the follow-up period, especially if it involves fever, rash, muscle aches, tiredness, malaise, or swollen glands. Such an illness or symptoms may suggest HIV infection, drug reaction, or other medical conditions.
  • You should contact your health-care provider if you have any questions or problems during the follow-up period.

What precautions should be taken during the follow-up period?

During the follow-up period, especially the first 6-12 weeks when most infected persons are expected to show signs of infection, you should follow recommendations for preventing transmission of HIV. These include refraining from blood, semen, or organ donation and abstaining from sexual intercourse. If you choose to have sexual intercourse, using a latex condom consistently and correctly may reduce the risk of HIV transmission. In addition, women should not breast-feed infants during the follow-up period to prevent exposing their infants to HIV in breast milk.

HIV Postexposure Prophylaxis Registry

What is being done to learn more about the use of antiviral drugs for treatment after an occupational exposure to HIV?

Because information is limited about the side effects/toxicity of antiviral drugs in uninfected people, like you, the Centers for Disease Control and Prevention, Glaxo Wellcome Inc., and Merck & Co., Inc., have begun the HIV Postexposure Prophylaxis (PEP) Registry, to collect information about the safety, tolerability, and outcome of taking antiviral drugs for postexposure treatment.

What kind of information will be collected by the Registry?

If you give permission, your health-care provider will provide information to the Registry about the exposure, the antiviral drugs taken, abnormal laboratory findings, and physical symptoms associated with the use of these drugs. Participation is voluntary and confidential. No information that would identify you will be collected.

How can I learn more about or enroll in the Registry?

Ask your health-care provider; he or she can obtain information about the Registry by calling toll-free 1-888-PEP4HIV-(1-888-737-4448).

Other Sources of Information

How can I learn more about health-care workers and occupational exposures to HIV?

Information specialists who staff the CDC National AIDS Hotline (1-800-CDC-INFO) can answer questions or provide information on HIV infection and AIDS and the resources available in your area. The AIDS Treatment Information Service (1-800-448-0440) can also be contacted for information on the clinical treatment of HIV/AIDS. For free copies of printed material on HIV infection and AIDS, please call or write to:
CDC National Prevention Information Network
P.O. Box 6003, Rockville, MD 20849-6003
Telephone 1-800-458-5231
Internet address:

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This article was provided by U.S. Centers for Disease Control and Prevention. Visit the CDC's website to find out more about their activities, publications and services.