From the Guidelines
Retesting for HIV is indicated after an initial test in several scenarios, including after potential new exposures, regardless of previous negative results, and for pregnant women who test negative early in pregnancy but have risk factors, who should be retested in the third trimester 1. When considering retesting for HIV, it's crucial to understand the context and the individual's risk factors.
- For individuals with ongoing risk factors, such as unprotected sex with multiple partners or injection drug use, regular testing every 3-6 months is recommended regardless of previous results.
- If the first test was negative but performed during the window period (typically within 3 months of potential exposure), retesting should occur at least 3 months after the exposure to ensure accuracy, as antibodies may take time to develop.
- If the initial test showed indeterminate or inconclusive results, immediate retesting with a different method is necessary.
- Following a positive screening test, confirmatory testing (usually Western blot or HIV RNA testing) should be performed to rule out false positives. These recommendations are based on guidelines that prioritize the health and well-being of individuals, particularly those at high risk of HIV exposure, and are supported by studies such as those published in the MMWR Recommendations and Reports 1. Key points to consider include:
- The importance of informed consent before HIV testing, as emphasized in the guidelines for HIV screening of pregnant women 1.
- The role of regular testing for individuals with ongoing risk factors, as discussed in the context of occupational exposures to HIV and recommendations for postexposure prophylaxis 1.
- The need for confirmatory testing after a positive screening test to ensure accurate diagnosis 1.
From the Research
Retesting for HIV
Retesting for HIV is indicated after the initial test in certain situations. The timing of retesting depends on various factors, including the type of test used and the individual's risk of exposure.
- The window period for HIV tests can range from 44 days for laboratory screening tests that detect both antigen and antibody to 65 days for the Western blot test 2.
- Point-of-care nucleic acid amplification testing (NAAT) can reduce the window period for detection to one week 3.
- For individuals who have been exposed to HIV, retesting is recommended after the window period has passed, typically 3 months after exposure 4.
- For infants and children aged 18 months or less, point-of-care nucleic acid-based testing (POC NAT) can be used to detect HIV-1/HIV-2 infection, with high sensitivity and specificity 5.
- The SAMBA II point-of-care nucleic acid test has shown high sensitivity, specificity, and concordance with gold standard assays, indicating its potential use in diagnostics and monitoring 6.
Timing of Retesting
The timing of retesting for HIV depends on the individual's risk of exposure and the type of test used.
- For individuals who have been exposed to HIV, retesting is recommended after the window period has passed, typically 3 months after exposure 4.
- For individuals who have been taking pre-exposure prophylaxis (PrEP) or antiretroviral therapy (ART), retesting may be recommended more frequently, as the window period may be affected by these medications 4.
- Point-of-care NAAT can be used to detect acute HIV infection and monitor individuals taking PrEP or ART, with results available in a shorter timeframe than traditional laboratory tests 3.