Dr. Jatin Ahuja details on the facets of pre- and post-exposure prophylaxis to prevent acquisiton of HIV and the recommended drug regimen for healthcare staff and patients.

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PrEP (pre-exposure prophylaxis) and PEP (post-exposure prophylaxis) both have the potential to reduce HIV transmission if used properly and consistently on the advice of a physician. Both are given to those people who don’t have HIV but are at risk of acquiring the infection.

PrEP is usually taken every day before the possible exposure to prevent acquisition of HIV either through sexual route or in those people who inject drugs (PWID). It’s been seen that consistent use of PrEP can reduce the risk of getting HIV by about 99% and in PWID by at least 74%.

PEP is usually given in emergency situations within 72 hours of potential possible exposure. PEP usually has 2 facets:

• Non-occupational PEP (nPEP)
• Occupational PEP (oPEP)

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Non-occupational PEP (nPEP):

To whom should nPEP be given to?

nPEP is usually for those who don’t have HIV but may have been exposed. Main indications for nPEP are:

• During condomless sex with a partner of unknown HIV status
• During sharing of injections in PWID
• In cases of sexual assault

What are the prerequisites prior to starting to nPEP?

Before prescribing the nPEP, the first step is to assess the need of the nPEP based on history and high risk sexual behaviour of the patient (exposure of vagina, rectum, other mucous membranes, blood or semen).

The second step is to conduct the rapid HIV blood test. In case the rapid HIV test (preferably 4th-generation HIV Ag/Ab test) is not available at the moment then nPEP can be started, however that can be discontinued if the patient turned out to be confirmed HIV positive.

nPEP is usually not recommended if the individual risk of exposure to HIV is not high or >72 hours have been passed since last potential exposure. Also, if feasible, it is better to know the HIV status of the source and level of exposure.

Specific regimens in nPEP

For a healthy individual the most common nPEP regimens last for 28 days (4 weeks), the course consisting of 3 drug combinations: Drug A+ Drug B+ Drug C.

• Drug A: Tenofovir disoproxil fumarate (TDF)- 300 mg, once daily
• Drug B: Lamivudine (3TC)- 300 mg, once daily OR Emtricitabine (FTC)- 200 mg, once daily
• Drug C: Dolutegravir (DTG)- 50 mg, once daily OR Raltegravir (RTG)- 400 mg twice daily OR Efavirenz (EFV)- 600 mg, once daily

Special care for sexual assault victims

For victims of sexual assault not only nPEP is required but also prophylaxis against Hepatitis B Virus (HBV) and sexually transmitted diseases (STDs) is required.

For victims who have not been previously vaccinated with Hepatitis B vaccine, require both Hepatitis B vaccine as well as Hepatitis B immunoglobulin (HBIG) at their first visit, followed by completing the schedule of Hepatitis B vaccine as per recommended schedule. Victims who previously have received the Hepatitis B vaccine and don’t know about their titres, usually single booster dose is recommended.

For prevention of common sexually transmitted diseases (STDs) such as gonorrhoea, chlamydia and trichomonas the following regimen is taken into consideration:

1. Gonorrhoea: Single dose of injection of Ceftriaxone 250 mg, intramuscular, along with a single dose of oral Azithromycin 1 g.
2. Chlamydia: Single oral dose of Azithromycin (given for gonorrhoea) or Doxycycline, 100 mg twice daily for 7 days.
3. Trichomonas: Tinidazole 2 g, single oral dose to be given

Labs testing prior to nPEP

1. Prior to starting nPEP, a pregnancy test should be done.
2. Rapid HIV test (preferably 4th-generation HIV Ag/Ab test) should also be done at the time of current visit, followed by 4-6 weeks and 3 months after nPEP initiation.
3. Also, the baseline testing for liver enzymes such as AST/ALT as well as renal parameters and serum creatinine should be done at baseline, 2 weeks and 4-6 weeks follow up if the patient is being given TDF-based therapy.
4. HCV antibody, HBsAg, HBV core antibody and anti Hbs antibody should be done at baseline. If negative, it should be repeated at the end of 6 months.

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Occupational PEP (oPEP)

oPEP is given after getting exposed while working, mainly after injury from needle stick in healthcare settings. In most of the cases, the risk of transmission of HIV in healthcare settings is very less with proper use of safety devices as well as following all barriers and precautions.

Follow up visit is required at 4 to 6 weeks, at 3rd month of starting nPEP repeat AST/ALT, serum creatinine, HIV test and VDRL test.

Specific regimens in oPEP

If you’re taking oPEP after being exposed at work, make sure that you let someone know about your injury. This can help your workplace to implement better precautions for the future. Regimens and duration (28 days) of nPEP is same as oPEP.

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Pre-exposure prophylaxis

PReP is the preventive therapy in which effective antiretroviral therapy is being taken by an individual without HIV and helps in reduction of contracting HIV. When taken consistently the levels achieved by effective antiretroviral therapy stops viral replication and later its establishment in the body.

In which individuals should PrEP be prescribed?

• In a HIV-negative individual who is in an ongoing sexual relationship with a HIV-positive partner who doesn’t have a undetectable viral load
• In an individual having condomless sex with multiple sexual partners and the HIV status of the partner is unknown
• In PWID with involvement of sharing needles to inject drugs

Does PrEP have a role in both vaginal as well as anal sex?

Yes, PrEP is effective in both types of sex; however there are different recommendations that have been proposed based on type of sex and gender.

One tablet per day regimen: In this, one tablet per day is to be started 7 days prior to exposure and then needs to be continued as long as protection is desired. It is indicated in the following individuals:

1. Women
2. Men having vaginal or anal sex with women
3. Gay and bisexual men

Event-based or on demand-based regimen: In this type of regimen, PrEP is taken before and after planned sex. It is usually recommended for gay and bisexual men. The main limitation of event-based regimen is that it needs to be started at least 2 hours before planned sex or need to delay the sex for 2 hours after taking PrEP.

The basic test requirement prior to start the patient on PrEP is to conduct an HIV test, as prescribing PrEP in already HIV-positive patient may lead to development of resistance.

1. Drug A+ Drug B (combined regimen is available in the market easily) for both vaginal as well as anal sex.
   1. Drug A: Tenofovir disoproxil fumarate (TDF)- 300 mg, once daily
   2. Drug B: Lamivudine (3TC)- 300 mg, once daily or Emtricitabine (FTC)- 200 mg, once daily
2. Drug A+ Drug B (combined regimen is available in the market easily) for only anal sex (because of poor concentration achieved by TAF in immune cells of vagina).
   1. Drug A: Tenofovir Alafenamide (TAF)- 25 mg, once daily
   2. Drug B: Emtricitabine (FTC)- 200 mg, once daily

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The views and opinions expressed in this article are those of the author and do not necessarily reflect the official policy or position of M3 India.

The author, Dr. Jatin Ahuja is an Infectious Diseases & Travel Health specialist.