HIV Acquisition, Timing, and Testing
Acute HIV is defined as the phase of HIV disease that occurs immediately after HIV acquisition and is characterized by detectable HIV RNA or HIV p24 antigen in the absence of anti-HIV antibodies.
- May be symptomatic (known as acute retroviral syndrome) or asymptomatic
- Characterized by high levels of viremia and an inflammatory surge
The recommended screening test for acute HIV is the HIV-1/2 antigen-antibody immunoassay (often written as HIV Ab/Ag combo); if negative, but high clinical suspicion remains, check HIV viral load PCR.
- Be wary of the eclipse phase: the short interval (10-12 days in duration) following HIV acquisition in which no diagnostic test is capable of detecting HIV.
Seroconversion is the point at which the body starts to produce detectable antibodies against HIV, but determining this point depends on the sensitivity of lab testing:
- IgM/IgG-sensitive HIV antibody tests detect HIV sooner than IgG-sensitive HIV antibody tests (~3 weeks vs 4-5 weeks, respectively)
PrEP vs PEP
Pre-exposure prophylaxis (PrEP) = Medication taken to reduce a person’s chance of contracting HIV, taken ahead of a behavior where they are at risk of contracting it (e.g., sex, needle use)
Post-exposure prophylaxis (PEP) = Medication taken to reduce a person’s chance of contracting HIV, taken after an exposure (e.g., sex, needle use, occupational exposure)
PEP
Any person whose vagina, rectum, eyes, other mucous membranes, compromised skin, or perforated skin has been contacted by contaminated secretions is eligible for PEP!
- Contaminated secretions: blood, semen, rectal/vaginal secretions, breastmilk
- Non-contaminated secretions: saliva, urine, nasal secretions, tears, sweat
HIV exposure is a MEDICAL EMERGENCY → PEP must be initiated as soon as possible (within 72 hours); PEP initiation should NOT be delayed while waiting for others’ test results.
- Specific cases: Should PEP be prescribed for a person who was exposed to high-risk body fluids…
- From another person whose HIV status is unknown?
- From a person with confirmed HIV, but exposure was >73 hours ago?
- From a person with HIV, but they’re already taking PrEP?
- From a person with HIV and a history of antiretroviral resistance?
- And is pregnant?
Work-up when initiating PEP:
- HIV Ag/Ab combo
- BUN/Cr (may need to renally dose PEP in presence of compromised renal function)
- LFTs
- Lipid panel
- Screening for chlamydia, gonorrhea, hepatitis B and C
- Pregnancy test (if applicable)
Essentially all people offered PEP should be prescribed a 28-day course of a 3-drug antiretroviral regimen.
PrEP
PrEP is highly efficacious. It can reduce HIV transmission risk by up to 99% from sexual exposures and 74-84% through injection drug exposures.
USPSTF recommends that clinicians offer PrEP to persons who are at high risk of HIV acquisition.
- Screen all adolescents and adults for PrEP eligibility during well-adolescent and well-adult visits
- Ask patients specifically about their sexual practices to assess transmission risk
- Patients who are interested in PrEP should be tested for HIV before initiating PrEP
- Patients with negative initial testing may need to be re-screened after several weeks depending on timing of recent exposures
Assessing indications for PrEP in sexually active people:
Assessing indications for PrEP in persons who inject drugs:
PrEP regimens:
FDA has approved three medications for use as PrEP:
- Emtricitabine (F) 200 mg in combination with tenofovir disoproxil fumarate (TDF) 300 mg (F/TDF – brand name Truvada) taken once daily by mouth
- Emtricitabine (F) 200 mg in combination with tenofovir alafenamide (TAF) 25 mg (F/TAF – brand name Descovy) taken once daily by mouth
- Cabotegravir (CAB) 600 mg injection (brand name Apretude) administered once every 2 months
These medications are approved to prevent HIV infection in adults and adolescents weighing at least 35 kg (77 lb) as follows:
- Daily oral PrEP with F/TDF is recommended to prevent HIV infection among all people at risk through sex or injection drug use
- Daily oral PrEP with F/TAF is recommended to prevent HIV infection among people at risk through sex, excluding people at risk through receptive vaginal sex. F/TAF has not yet been studied for HIV prevention for people assigned female at birth who could get HIV through receptive vaginal sex
- Injectable PrEP with CAB is recommended to prevent HIV infection among all people at risk through sex. It may be especially useful for people who have problems taking oral PrEP as prescribed, who prefer getting a shot every 2 months instead of taking oral PrEP, or who have serious kidney disease that prevents use of oral PrEP medications
“On-demand” PrEP can be prescribed via 2-1-1 dosing, as previously discussed here.
Key considerations when prescribing PrEP:
- Contraindications: Anaphylaxis/hypersensitivity
- Precautions:
- Raltegravir associated with SJS/TEN
- Tenofovir associated with renal toxicity
- Emtricitabine associated with hyperpigmentation (kids > adults)
- Nucleoside analogues associated with severe hepatomegaly and lactic acidosis
- Immune reconstitution syndrome if HIV+
- Various drug interactions (especially AEDs)
- Must have documented negative HIV Ab/Ag combo within a week of starting PrEP
- Key history: any exposure event in the last 4 weeks? with signs/symptoms of acute infection?
- If yes, test for viral load (PCR) as well
Work-up when initiating PrEP:
- HIV Ab/Ag combo
- BUN/Cr
- Lipid panel
- Screening for chlamydia and gonorrhea (both from 3 sites), hepatitis B and C, syphilis
- Pregnancy test (if applicable)
Other considerations:
- Fixed-dose pills come up in Epic when you search the brand name!
- Due to monitoring intervals, we should send no longer than a 90-day supply
- Affordable Care Act requires most insurance plans to cover PrEP
- If financial barriers persist, TMH Immunology has a PrEP Patient Assistance Program which can waive bills for patients who can’t pay
- Cabotegravir is available through TMH Immunology for adults and Adolescent Medicine for teens
- Creatinine clearance not an issue
- Patients may switch from oral to injectable PrEP at any time as long as they remain HIV negative at time of switch
- FDA approval has no lower age limit, only “adolescents >35 kg”
- In RI, minors can legally consent themselves for HIV testing and treatment
Monitoring patients on PrEP:
- All patients on PrEP require q3 month follow-up visits
- At each 3 month visit, providers should:
- Assess for signs/symptoms of acute HIV infection
- Repeat HIV Ab/Ag combo (consider PCR test if patient has symptoms)
- Counsel on adherence and risk reduction
- At 6-month intervals: repeat renal function testing
- At 12-month intervals: repeat lipid panel and monitor weight (especially those on Descovy)
- STI screening frequency can vary based on sexual activity (minimum q12 months)
Take-Home Points!
- Screen all adolescents and adults for PrEP eligibility during well visits, plus during any relevant follow-up visits.
- All patients on PrEP require regular follow-up, preferably every 3 months
- Any person whose vagina, rectum, eyes, other mucous membranes, compromised skin, or perforated skin has been contacted by contaminated secretions is eligible for PEP.
Blog post based on Med-Peds Forum talk by Emily Kruse, PGY2, and Laura Schwartz, PGY2