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Customize the content by gender, HIV status, and gender of sex partner

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Explore customized information about the risk of getting or transmitting HIV

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About the Data

About the Data

About “Estimate the HIV Risk”

Every time a person with HIV who is not virally suppressed has sex with an HIV-negative person,there is a chance the HIV-negative partner will get HIV. Some sex acts (such as, kissing, touching, and oral sex) have extremely low to no HIV risk. You have a much higher risk for getting or transmitting HIV through vaginal and anal sex.

Estimate the HIV Risk shows risks when one partner has HIV and the other partner doesn’t. It gives you information for a single sex act at a time. You can change the settings on the tool to get information about a variety of sex acts, to see how one type of sex act is riskier than another.

Choosing to use protective factors (such as condoms, pre-exposure prophylaxis or PrEP , and antiretroviral therapy, or ART) can lower or eliminate the HIV risk for each sex act. This tool provides information on how much each protective factor reduces HIV risk.

Other risk factors (such as having an acute HIV infection or having another STD) can raise the HIV risk for each sex act.  This tool also provides information on how much each risk factor increases HIV risk.

Estimate the HIV Risk can give you different kinds of HIV risk information. It can show you:

  • The HIV risk for different sex acts
  • Which sex acts are riskier than others
  • How different protective factors reduce HIV risk
  • How different risk factors increase HIV risk

About the Numbers

If you click on “Show numbers,” you will see the number of times HIV could be transmitted for every 10,000 sex acts. The numbers may seem small, but they show the risk for one sex act. Your risk for getting or transmitting HIV increases every time you have sex with a discordant partner (a partner with a different HIV status).

Sexual activities

Estimate the HIV Risk displays the number 138 for the risk of getting HIV from receptive anal sex. This represents that the risk for getting HIV from receptive anal sex (without condoms, PrEP, or ART) is about 138 per 10,000 sex acts. So, on average for an HIV-negative receptive partner, there is about a 1 in 72 chance of getting HIV for every act of receptive anal sex with an HIV-positive insertive partner. In the anal sex message of the HIV Risk Reduction Tool, the risk is displayed as 1 in 72.

This table outlines how the risk numbers for the other activities in Estimate the HIV Risk are displayed with the messages of the HIV Risk Reduction Tool.

Activity

Risk Displayed in Know the HIV Risk

Risk Displayed in the HIV Risk Reduction Tool Messages

Receptive Anal Sex

138

1 in 72

Insertive Anal Sex

11

1 in 909

Receptive Vaginal Sex

8

1 in 1250

Insertive Vaginal Sex

4

1 in 2500

Patel, P., Borkowf, C. B., Brooks, J. T., Lasry, A., Lansky, A., & Mermin, J. (2014). Estimating per-act HIV transmission risk: a systematic review. AIDS, 28(10), 1509-1519. doi: 10.1097/QAD.0000000000000298

Protective Factors
The three protective factors in Estimate the HIV Risk are condoms, PrEP, and ART. Each protective factor is assigned a numerical value that expresses the best estimates of effectiveness for that factor. The studies on the effectiveness of these factors use different methodologies and measures, and have been conducted in different populations. The numbers selected for use in Estimate the HIV Risk were chosen to try to minimize study differences; i.e. they are as comparable across activities and populations as possible.
Choosing protective factors in Estimate the HIV Risk will illustrate how much the factor decreases the risk of HIV transmission for each act. For example, for receptive anal sex with optimal or consistent PrEP use, Estimate the HIV Risk will display about a 99% HIV risk reduction, which reduces the risk of transmission from 138 per 10,000 exposures to about 1 per 10,000 exposures.
The tables below display the estimated risk of an activity when applying the estimated reduction in risk for the protective factor. For all values between of estimated risk than fall between 0 and .5, the Estimate the HIV Risk graphic will display “ <.5.” on the flag. Estimate the HIV Risk graphic displays the decrease in estimated risk as the area of the triangle shaded green.
 
Risk of Getting HIV example
 
Additional details about these tables, including sources and principles for selecting the estimates can be found CDC’s HIV Risk and Prevention Estimates webpage: https://www.cdc.gov/hiv/risk/estimates/index.html

PrEP

Protective Factor: Optimal or Consistent PrEP for the HIV negative partner
Activity

Risk Displayed in Estimate the HIV Risk

HIV Risk Reduction Estimate

Estimated Risk of Activity with Protective Factor

Activity with Protective Factor as Displayed in Estimate the HIV Risk

Receptive Anal Sex

138

∼99%

1.38

1

Insertive Anal Sex

11

∼99%

.11

<.5

Receptive Vaginal Sex

8

∼99%

.08

<.5

Insertive Vaginal Sex

4

∼99%

.04

<.5

 

Male Condoms

Protective Factor: Male Condoms for the insertive partner
Activity

Risk Displayed in Estimate the HIV Risk

HIV Risk Reduction Estimate

Estimated Risk of Activity with Protective Factor

Activity with Protective Factor as Displayed in Estimate the HIV Risk

Receptive Anal Sex

138

72%

38.64

39

Insertive Anal Sex

11

63%

4.07

4

Receptive Vaginal Sex

8

80%

1.60

2

Insertive Vaginal Sex

4

80%

.80

1

ART+UVL

Protective Factor: ART+UVL for the HIV-positive partner
Activity

Risk Displayed in Estimate the HIV Risk

HIV Risk Reduction Estimate

Estimated Risk of Activity with Protective Factor

Activity with Protective Factor as Displayed in Estimate HIV Risk

Receptive Anal Sex

138

100%

0

0

Insertive Anal Sex

11

100%

0

0

Receptive Vaginal Sex

8

100%

0

0

Insertive Vaginal Sex

4

100%

0

0

* There is effectively no risk of HIV transmission if the partner with HIV gets and keeps an undetectable viral load.

Risk Factors

The risk factors in Estimate the HIV Risk are either partner having another STD, and acute infection. The risk factors are assigned numerical values that express the increase in risk for HIV transmission with the risk factor.

Choosing risk factors in Estimate the HIV Risk will illustrate how much the factor increases the risk of HIV transmission for each act. For example, for receptive anal sex with Acute HIV Infection, Estimate the HIV Risk will display that the HIV risk increases by 7.25, which increases the risk of transmission from 138 per 10,000 exposures to 1001 per 10,000 exposures.

Estimate the HIV Risk displays the increase in estimated risk as the area of the triangle shaded red.

Additional details about these tables can be found on the CDC’s HIV Risk and Prevention Estimates webpage.

Acute HIV Infection

Risk Factor: Acute HIV Infection for the HIV-positive partner
Activity

Risk Displayed in Estimate the HIV Risk

HIV Risk Estimate

Estimate Risk of Activity with Risk Factor

Activity with Risk Factor as Displayed in Estimate the HIV Risk

Receptive Anal Sex

138

7.25

1000.50

1001

Insertive Anal Sex

11

7.25

79.75

80

Receptive Vaginal Sex

8

7.25

58

58

Insertive Vaginal Sex

4

7.25

29

29

 

STDs

Risk Factor: STD infection for the HIV-negative partner
Activity

Risk Displayed in Estimate the HIV Risk

HIV Risk Estimate

Estimated Risk of Activity with Risk Factor

Activity with Risk Factor as Displayed in Estimate the HIV Risk

Receptive Anal Sex

138

2.65

365.70

366

Insertive Anal Sex

11

2.65

29.15

29

Receptive Vaginal Sex

8

2.65

21.20

21

Insertive Vaginal Sex

4

2.65

10.60

11

 

Risk Factor: STD infection for the HIV-positive partner
Activity

Risk Displayed in Estimate the HIV Risk

HIV Risk Estimate

Estimate Risk of Activity with Risk Factor

Activity with Risk Factor as Displayed in Estimate the HIV Risk

Receptive Anal Sex

138

2.58

356.04

356

Insertive Anal Sex

11

2.58

28.38

28

Receptive Vaginal Sex

8

2.58

20.64

21

Insertive Vaginal Sex

4

2.58

10.32

10

 

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