What is the recommended protocol for HIV testing?

HIV Testing Protocol

All patients aged 13-64 years should undergo routine opt-out HIV screening in all healthcare settings using a fourth-generation antigen/antibody combination assay as the initial test, followed by confirmatory testing with HIV-1/HIV-2 antibody differentiation immunoassay if reactive. 1, 2

Initial Screening Approach

Universal Screening Recommendations

• Routine opt-out screening should be performed for all patients aged 13-64 years in all healthcare settings, meaning patients are informed that HIV testing will be performed unless they decline 3, 2
• Screening should be initiated unless HIV prevalence in the patient population is documented to be <0.1%, or the diagnostic yield is <1 per 1,000 patients screened 3
• No separate written consent is required—general informed consent for medical care is sufficient, and prevention counseling is not mandatory as part of screening 3
• Patients should be notified orally or in writing that testing will be performed, with explanation of HIV infection and test result meanings, and offered opportunity to ask questions or decline 3

Preferred Testing Method

• Fourth-generation HIV antigen/antibody combination assay is the recommended initial screening test, as it simultaneously detects HIV p24 antigen and HIV antibodies with >99.5% sensitivity and specificity 1, 2
• This assay allows earlier diagnosis (4-7 days after detectable virus) compared to antibody-only tests, reducing the window period by approximately 4 days 1
• Rapid HIV tests can be used in episodic care settings (emergency departments, urgent care, STD clinics) where follow-up is challenging, but positive results must be confirmed 3

Confirmatory Testing Algorithm

Step-by-Step Confirmation Process

1. If initial screening is reactive: Perform HIV-1/HIV-2 antibody differentiation immunoassay to distinguish between HIV-1 and HIV-2 infections 1, 4

2. If differentiation assay is positive: HIV infection is confirmed—proceed to baseline evaluation and treatment 4

3. If differentiation assay is negative or indeterminate: Perform nucleic acid amplification testing (NAAT/HIV RNA) to rule out acute HIV-1 infection 1, 4

4. Critical caveat: Never disclose a positive HIV diagnosis based on screening test alone without confirmatory testing, as false positives can have devastating psychological and social consequences 4, 2

Traditional Algorithm (Still Valid)

• The traditional approach uses ELISA for initial screening, followed by Western blot for confirmation if repeatedly reactive 4, 5
• A positive Western blot confirms HIV infection; negative Western blot indicates no infection unless acute infection is suspected 4
• Indeterminate Western blot requires follow-up testing at 4-6 weeks and consideration of HIV RNA testing 4

High-Risk Populations Requiring More Frequent Testing

Annual Screening Indicated For:

• Men who have sex with men and active injection drug users (at least annually, or every 3 months if very high risk) 2
• Persons with unprotected vaginal or anal intercourse 2
• Sex partners of HIV-infected persons or injection drug users 2
• Persons exchanging sex for drugs or money 2
• Anyone requesting STD testing 2
• All patients initiating tuberculosis treatment 3
• All patients seeking STD treatment (test at each visit for new complaint) 3

Third Trimester Repeat Testing for Pregnant Women:

• All pregnant women should be tested as early as possible during pregnancy using opt-out screening 3
• Repeat testing in third trimester (preferably <36 weeks) is recommended for: 3
  • Women in jurisdictions with elevated HIV/AIDS incidence 3
  • Women in facilities identifying ≥1 HIV-infected pregnant woman per 1,000 screened 3
  • High-risk women (injection drug users, sex workers, HIV-infected partners, new/multiple partners during pregnancy) 3
• Rapid testing during labor for any woman with undocumented HIV status, with immediate antiretroviral prophylaxis if reactive without awaiting confirmation 3

Special Testing Situations

Acute HIV Infection Suspicion

• When acute retroviral syndrome is suspected (compatible clinical syndrome with recent high-risk behavior), use plasma RNA test in conjunction with HIV antibody test 3
• Fourth-generation assays detect acute infection earlier than antibody-only tests, but NAAT may still be needed 1

Post-Exposure Prophylaxis (PEP) Context

• For persons with recent high-risk exposure within 72 hours, perform both laboratory-based antigen/antibody test and HIV NAAT 1
• Avoid oral fluid-based rapid tests in PEP contexts, as they are less sensitive for acute/recent infection than blood-based tests 2
• Follow-up testing at 4-6 weeks after PEP initiation should include both antigen/antibody test and diagnostic NAAT 1

Infants Born to HIV-Positive Mothers

• Do not use antibody tests for infants <15-18 months due to maternal antibody transfer 1, 4, 2
• Definitive diagnosis requires two positive HIV RNA PCR or viral culture tests on separate specimens 4, 2
• Neonatal antiretroviral prophylaxis benefits are maximized when initiated <12 hours after birth 3

HIV-2 Testing Considerations

• Consider HIV-2 testing for persons from endemic regions (West Africa), their sexual partners, or when clinical evidence suggests HIV disease but HIV-1 tests are negative 4, 2
• If HIV-2 ELISA is repeatedly reactive with negative/indeterminate HIV-1 Western blot, send specimen to state public health laboratory for HIV-2 supplemental testing 4

Result Communication and Follow-Up

Delivering Test Results

• Negative results may be conveyed without direct personal contact 3
• Positive results must be communicated confidentially through personal contact by clinician, nurse, mid-level practitioner, or counselor—never use family/friends as interpreters due to stigma risk 3
• Active efforts are essential to ensure HIV-infected patients receive results and linkage to clinical care, counseling, and prevention services 3

Post-Diagnosis Requirements

• All persons with confirmed HIV infection must receive comprehensive baseline testing including HIV RNA viral load, CD4 count, genotypic resistance testing, HLA-B*5701 testing, and screening for coinfections (hepatitis B/C, TB, STDs) 2
• Immediate antiretroviral therapy should be offered to all diagnosed persons regardless of CD4 count or viral load 2
• Behavioral and psychosocial services should be provided as integral part of care 4

Common Pitfalls to Avoid

• Window period false negatives: Antibody tests cannot rule out infection <6 months before testing, as HIV antibody is detectable in ≥95% of patients within 6 months 4
• Rapid test limitations: While convenient, rapid tests have shown lower sensitivity (77.5%) compared to ELISA in some studies, missing acute infections 6
• Documentation: If patient declines testing, document this decision in the medical record 3
• HIPAA compliance: Never disclose patient's HIV status without permission 3