1. Acute HIV Infection and PrEP: Opportunities and challenges
Meg Doherty MD MPH PhD
WHO HQ
Acute HIV Infection Symposium, IAS 2018 Conference, Amsterdam, Netherlands
23 July June 2018

2. Testing for acute HIV infection while taking PrEP

3. Testing in the context of PrEP
People who start PrEP need to have received a negative HIV test result, and then offered testing every 3 months while they continue on PrEP to make sure that they have not acquired HIV.  
WHO advises testing using the most sensitive tests (as per national testing strategy) for the A1 test – usually a 3rd generation test. 
Reports of delays in antibody response in people who have seroconverted while on PrEP (due to poor adherence to the prescribed regime) when 2nd generation oral fluid tests have been used for follow up monitoring. 
Oral fluid tests are not advised for PrEP monitoring. 

4. Possible Ways to Screen for Acute Infection in PrEP Programs
When Starting or Restarting PrEP
Symptoms of acute viral syndrome
HIV Ag assays
HIV nucleic acid testing
During Follow-up
Verify effective use
If non-adherent, test as if restarting PrEP

5. Clinical Screening for Acute Viral Syndromes and Acute HIV infection in iPrEx OLE
No HIV
Acute HIV
No Sx
1573 Sx 28 2 30
1601
1603
Eligible for PrEP
N=1603
Deferred PrEP due to
Acute Viral Syndrome
N=30 (1.9%)
Sensitivity = 100%
Specificity = 98%
PPV = 6.7%
NPV = 100%
Acute HIV infections
N=2 (6.7%)
HIV RNA negative
N=28 (93.3%)
Delayed Start on PrEP
N=25 (83.3%)
Never started PrEP
N=3 (6.7%)
Grant et al, Lancet ID, 2014.

6. 4th generation assays and NAT technologies?
The risk of acute infection in people who seek PrEP services is expected to range between 1:50 and 1:300 at baseline depending on the underlying HIV incidence in the population.
Early detection of HIV, NAT can help identify acute infection, allows earlier diagnosis and linkage to ART, ↓risk of developing HIVDR from starting PrEP while acutely infected.
Because of this risk and where feasible, there may be benefits to using assays that have the ability to detect HIV earlier, such as 4th generation serology assays that detect HIV-1/2 antibodies and HIV p24 antigen, and NAT technologies, for HIV testing prior to starting or restarting PrEP.