How infectious is HIV?
HIV is not as infectious as some other viral diseases. If you have sex with someone with HIV and are exposed to the virus, it does not necessarily mean that you will become HIV-positive.

  • Some research shows that the likelihood of HIV transmission when a negative man having sex without condoms with an HIV-positive man, with a detectable viral load, is around 1% (one time in every 100) [1].
  • HIV is more likely to be transmitted if the HIV-positive man has a high viral load, which is more likely if he is not on treatment, or if either partner has another STI [2].
  • It's important to remember that while some people have sex without condoms many times before they get HIV, some people get infected after just one unprotected session.
  • The likelihood of exposure from oral sex resulting in HIV transmission is extremely low.

How do I protect myself from HIV?
You can protect yourself or your partner from HIV by ensuring that exposure to HIV doesn’t happen, or by reducing the likelihood of transmission if HIV exposure does happen.

Methods for preventing HIV exposure include:

  • using condoms
  • using PrEP
  • only having sex with other men you are certain are HIV-negative (sero-sorting)
  • only having non-penetrative sex, such as wanking.
  • having sex with someone who is HIV-undetectable.

 
Methods for reducing the likelihood of transmission if you are exposed to HIV include:

  • medical preventions, such as PEP, PrEP 
  • relying on the positive partner not infectious as a result of an undetectable viral load - this is know as HIV-undetectable or U=U.

 
Other methods which reduce the likelihood of transmission include:

  • withdrawal (the positive partner not cumming inside the negative partner)
  • strategic positioning (the positive partner being the bottom in penetrative sex).

 
Condom use and all of the methods of reducing the likelihood of transmission are not 100% guaranteed to prevent transmission. 


What if I’ve been exposed to HIV?
If you think you have been exposed to HIV in the past 72 hours, taking post-exposure prophylaxis (PEP) may be able to stop you from becoming infected. PEP is only likely to be effective in the first 72 hours after exposure.


LAST UPDATED: 6 September 2019

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References:
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1 Jin F, Jansson J, Law M, Prestage GP, Zablotska I, Imrie JCG, Kippax SC, Kaldor JM, Grulich AE, Wilson DP. Per-contact probability of HIV transmission in homosexual men in Sydney in the era of HAART. AIDS, 2010;24(6):907-913.
2 Zuckerman RA, Whittington WLH, Celum CL, Collis TK, Lucchetti AJ, Sanchez JL, Hughes JP, Sanchez JL, Coombs RW. Higher concentrations of HIV RNA in rectal mucosa secretions than in blood and seminal plasma, among men who have sex with men, independent of antiretroviral therapy. Journal of Infectious Diseases, 2004;189:156-161.