What is the recommended protocol for HIV screening in emergency department patients aged 13‑64, including opt‑out consent, rapid fourth‑generation antigen/antibody testing, and management of positive results and post‑exposure prophylaxis?

HIV Screening in the Emergency Department

All emergency department patients aged 13-64 years should receive routine opt-out HIV screening using a fourth-generation antigen/antibody combination test, unless the patient actively declines or local HIV prevalence is documented to be <0.1%. 1

Screening Protocol

Who to Screen

• Universal screening: All patients aged 13-64 years presenting to the ED 2, 1
• Exclusions:
  • Patients with known HIV diagnosis
  • Those tested for HIV within the past 12 months
  • Altered mental status or inability to consent
  • Documented local HIV prevalence <0.1% 1

Consent Process

The CDC's "opt-out" approach is not truly passive consent—it requires specific steps 1:

• Inform patients orally or in writing that HIV testing will be performed
• Explain HIV infection and the meaning of positive/negative results
• Offer opportunity to ask questions
• Allow patients to decline testing
• Document refusal in the medical record if declined
• No separate written consent form is required—incorporate into general medical consent 1

This approach significantly increases acceptance rates: opt-out consent achieves 78% acceptance versus 63% with opt-in consent 3.

Testing Technology

Preferred Test: Fourth-Generation Antigen/Antibody

Use a rapid fourth-generation antigen/antibody combination HIV test 4, 5

Critical advantage: Fourth-generation testing detects acute HIV infection that earlier tests miss. In one ED screening program, 23% of all new HIV diagnoses were acute infections that would have been missed with older technology 4. Acute HIV represents the most infectious period and highest transmission risk.

Testing Options

• Laboratory-based fourth-generation Ag/Ab test (preferred for accuracy and acute infection detection)
• Rapid point-of-care tests (acceptable but may miss acute infections)
• Consider both if resources allow—blood-based fourth-generation testing identified more cases than oral POC testing alone 5

Management of Positive Results

Immediate Actions

1. Deliver results confidentially through personal contact by a physician or trained staff member 1
2. Perform confirmatory testing on the same specimen when possible 4
3. Assess for acute HIV if fourth-generation test is reactive—look for:
   • High viral load
   • Recent negative test (within 1-6 months)
   • Symptoms: fever, pharyngitis, rash, lymphadenopathy 4

Linkage to Care

Establish formal linkage protocols before implementing screening 6:

• Designate linkage-to-care specialists or infectious disease consultation
• Arrange follow-up appointments within 24-72 hours 5
• Document linkage attempts in medical record
• Target: >90% linkage rate is achievable with dedicated protocols 5

Critical pitfall: In early ED screening programs, 50% of newly diagnosed patients were lost to follow-up without formal linkage protocols 7. This is unacceptable—screening without linkage causes harm.

Post-Exposure Prophylaxis (PEP)

When to Offer PEP

Initiate PEP within 72 hours for substantial HIV exposure risk 8:

• Sexual exposure: Receptive or insertive anal/vaginal intercourse with known HIV-positive source (or unknown status in high-prevalence setting)
• Parenteral exposure: Needlestick, sharing injection equipment
• Mucous membrane exposure: Blood or genital secretions to eyes, nose, mouth

PEP Regimens (2025 Guidelines)

Preferred regimens for 28 days 8:

1. Bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) - single daily tablet
2. Dolutegravir (DTG) + (tenofovir alafenamide OR tenofovir disoproxil fumarate) + (emtricitabine OR lamivudine)

PEP Protocol

• Baseline testing: Fourth-generation Ag/Ab HIV test plus diagnostic NAT if patient had long-acting injectable PrEP in past 12 months 8
• Do not delay PEP for test results if exposure occurred <72 hours ago
• Follow-up testing:
  • 4-6 weeks: Ag/Ab + NAT
  • 12 weeks: Ag/Ab + NAT (final) 8
• Monitor for adherence and toxicity at 72 hours and 2 weeks 9

Implementation Considerations

Workflow Integration

Integrate screening into triage workflow rather than using supplemental staff only 5, 10:

• Embed HIV screening prompts in electronic medical records
• Use best practice alerts (BPAs) to trigger screening for eligible patients 11
• Train triage nurses to offer testing during routine blood draws
• This approach increased testing rates from 14.6% to 16.6% and identified more cases 5

Required Resources

Do not implement screening without 6:

• Adequate funding for personnel and operational costs
• Pre- and post-test counseling capacity
• Linkage-to-care infrastructure with HIV treatment providers
• Staff training on consent process and result delivery
• Confidentiality protections meeting state requirements

Common Pitfalls to Avoid

1. Assuming risk-based screening is sufficient: 10-25% of HIV-positive patients report no risk factors 12
2. Using older test technology: Misses 23% of cases (acute infections) 4
3. Screening without linkage protocols: Results in 50% lost to follow-up 7
4. Requiring separate written consent: Creates barrier, reduces acceptance 1
5. Deferring testing to primary care: Only 6-8% get tested at follow-up 13

State Law Compliance

Verify state-specific requirements before implementation, as HIV testing laws vary 7. However, most states' laws are now consistent with CDC opt-out recommendations.

The evidence strongly supports that ED-based HIV screening with fourth-generation testing, opt-out consent, and robust linkage-to-care protocols identifies undiagnosed infections (including highly infectious acute cases), improves individual outcomes through early treatment, and reduces community transmission 2, 1, 4.