HIV risk after sex with a sex worker

Why the partner matters most

Your risk from any single act depends on two things: the chance your partner has HIV, and the chance the act passes it on. Paying for sex doesn’t change the second part. A condom does, and so does the type of sex.

What’s different is the first part. A review of 102 studies covered nearly 100,000 female sex workers in 50 low- and middle-income countries. It found they were about 13.5 times as likely to have HIV as women of reproductive age generally. The calculator uses that figure when you tell it your partner was a sex worker. Rates vary a great deal between countries and settings, so the figure is a rough guide, not a fact about any one person.

Estimates for one act

For a man having vaginal sex once with a female sex worker of unknown status:

• United States, no condom: 0.00088% (about 1 in 110,000)
• United States, with a condom: 0.00018% (about 1 in 570,000)
• Thailand, no condom: 0.00072% (about 1 in 140,000)
• South Africa, no condom: 0.0079% (about 1 in 13,000)

Being circumcised lowers a man’s risk in vaginal sex. The calculator reduces the estimate by 50%, so the United States figure without a condom becomes 0.00044% (about 1 in 230,000).

For a man bottoming with a male sex worker of unknown status in the United States, without a condom, the estimate is 0.05% (about 1 in 2,000). Anal sex carries more risk than vaginal sex; see HIV risk from anal sex.

Receiving oral sex carries very little risk, because HIV isn’t passed on through saliva. See HIV risk from oral sex.

Condoms make the biggest difference

In real-world use, including occasional breaks and slips, condoms lower the risk of sex by about 80%. If a condom was used the whole time and stayed intact, your risk is very low. If it broke, slipped or came off, count that act as unprotected and read what to do if a condom broke.

Things that raise the risk

• Other STIs. Sores and inflammation make HIV easier to pass on. The calculator multiplies the estimate by 2 if either of you has one.
• More than one act or more than one partner. Each exposure is another chance. See repeated exposures.

What to do now

1. If a condom wasn’t used or failed, and it was within 72 hours, go for PEP. Be honest with the clinician about what happened. They’re there to help, not to judge, and the details decide whether PEP is recommended. PEP is taken daily for 28 days.
2. Don’t wait for a test first. A test now can’t show an infection from this exposure. The clinic will do a baseline test, and you can start PEP before the result is back.
3. Test after the window period. A NAT (nucleic acid test) can detect HIV from 10 days. A lab antigen/antibody test (blood from a vein) gives a conclusive negative from 45 days. If you take PEP, expect follow-up tests about 4 to 6 weeks and 12 weeks after the exposure. See test accuracy by week.
4. Get an STI check. Sex without a condom, or with one that failed, can pass on other infections too.
5. Plan ahead. If paid sex is something you do more than once, ask about PrEP (pre-exposure prophylaxis). Taken as prescribed, it lowers the risk by about 90% for vaginal sex and about 99% for anal sex. Condoms protect against other STIs as well.