Post Exposure Prophylaxis – How to prevent HIV and other STDs

Post-exposure prophylaxis (PEP) is a preventive healthcare medication given to individuals who are at risk of getting infected with a pathogen due to accidental exposure to the pathogen.



Post Exposure Prophylaxis


However, aside from Post Exposure Prophylaxis for HIV, there is also prophylaxis for sexually transmitted diseases (STDs) such as; Syphilis, Gonorrhea, Hepatitis, Chlamydia, and Trichomonas infections.

Occupational Post Exposure Prophylaxis (OPEC) occurs in individuals who work in health facilities, it is the risk of contracting HIV while carrying out their legitimate duties such as needle prick or contact with the infectious fluid of an HIV patient.

There is also a non-occupational Post Exposure Prophylaxis (nPEP) for individuals who have exposures like a condom break, unprotected sex with an HIV-positive person, or indiscriminate sharing of syringes as seen in drug addicts.

Nevertheless, Rape and sexually assaulted victims also receive post-exposure prophylaxis medications against HIV, other STDS, and also contraceptives to prevent unwanted pregnancy.


HIV Post Exposure Prophylaxis

PEP is a combination of 3 ART drugs unlike the use of Zidovudine alone. It is offered to individuals within 72 hours of exposure to prevent seroconversion of the viral particles from occurring.

It’s important to note that PEP should not be encouraged if the individual is to have a continuous exposure, instead Pre Exposure prophylaxis (PrEP) should be considered to avoid causing resistance to the ART if seroconversion has already occurred.

Steps for initiating HIV PEP

According to the Center for Disease Control and Prevention (CDC), PEP initiation involves the steps below;

1) Determine HIV status and risk of exposure

HIV status of the exposed, If positive, there is no need for PEP instead commencement of enrollment to HAART.

Information about the source is important such as;

  • The HIV status of the source
  • The level of viral suppression?
  • WHO stage of the disease

All this information gives an idea of the potential risk of transmission from the source.


The best results from PEP are within 72 hours of initiation after exposure. If the exposure time exceeds 72 hours, there is a doubt to commence PEP because once seroconversion has occurred, stopping PEP after 28 days and the patient is positive after 3 months, the virus may develop resistance to the agents used earlier for PEP.

The nature and risk of exposure:

Exposures involving blood, fluids containing visible blood, or other potentially infectious fluids on intact skin do not require PEP. If the skin is compromised such as in dermatitis, the volume of the fluid and duration of the contract is considered.
A percutaneous injury such as a needle prick or abrasion from a contaminated sharp object is low risk if it’s a solid needle and a superficial scratch but,Ā  a percutaneous injury that is deep from a hollow needle is high-risk exposure.

2. Consider eligibility for PEP?

Body fluids or blood on intact skin for a short period is not eligible for PEP.

Exposure from a patient who is asymptomatic by the WHO staging with a small volume of blood or fluid on a compromised skin does not warrant a PEP unless the duration of the contract is long or the fluid is of large volume.

However, exposure from an asymptomatic patient with high viral load irrespective of the fluid volume or duration of contact should receive PEP.

Percutaneous injury from needle prick of all sorts is eligible for PEP. Injuries that show visible blood on the instrument, deep or from a hollow needle have a greater risk of exposure.

3. Regimen design for PEP

2 NRTIs are always regarded as the backbone of every PEP but the addition of a 3rd agent gives a broader spectrum and proves more effective, especially for some resistant strains of the virus.

  1. Tenofovir (TDF) + Lamivudine (3TC)
  2. Zidovudine (AZT) + Lamivudine (3TC)
  3. Abacavir (ABC) + Lamivudine (3TC)

These combination regimens have proved to be effective in use for PEP for both adults and children.
However, In children <10 years, Efavirenz (EFV) is recommended for PEP. Lopinavir/ritonavir or Atazanavir/ ritonavir is a better option where EFV is not suitable such as mental illness.

Note: Nevirapine is not to be used for Post Exposure prophylaxis as the risk of fatal hepatoxicity outweighs the risk of HIV infection.

Factors to consider before a regimen design

These factors listed below can influence adherence and hence, the effectiveness of the Post Exposure Prophylaxis

Disease-drug interaction

The clinician should always bear in mind that some disease conditions contraindicate the use of some drugs. examples of such interactions exist between Zidovudine and Anaemia, Tenofovir, and Nephritis. However, AZT + 3TC is a good choice when laboratory data on disease states are not available.

Pill burden/adherence

TDF + 3TC or ABC + 3TC shows to provide a better adherence since it’s a once in a day dosing, unlike AZT + 3TC which is twice a day dosing. Also, Lopinavir/ritonavir has more pill burden than EFV.

Side effects of the drugs

The PEP receiver should be part of the decision-making process on the drug combinations best for him/her with regards to the side effects they present.

4. Proper counseling on the need for adherence

The major setback to an effective PEP is non-adherence. Strong emphasis is on the need to complete the 28 days of therapy. The health care provider should also educate the patient on the possible side effects of the drugs and the need to seek medical assistance if there are any.

5. Follow up and monitoring of adverse drug reactions

Proper follow-up will create a very encouraging relationship that can improve adherence and pharmacovigilance. Also, monitoring of individuals is important in discovering possible side effects or drug therapy problems that may interfere with taking ARV drugs or adherence problems.

6. Re-test after every 3 months

A test after 3 months of exposure is important, the test being negative can be a conclusive diagnosis but a repeat test again after another 3 months is essential to rule out all possible probabilities. However, researchers with Fourth-generation HIV tests can detect HIV infection in 50% of people by 18 days after infection; 95% of people by 34 days after infection; and 99% of people by one and a half months after infection.

Reasons why PEP fail

There are plenty of reasons why a PEP fails. Some of these reasons are dependent on the caregiver, some on the choice of regimen, and others are on the victim receiving the PEP.

Here, are the most common causes of PEP failure. There may be other factors that can influence failure such as social status, environmental factors, Lifestyle e.t.c.

However, we are going to list some of the reasons why PEP fails. Your healthcare provider will provide you with more details on things that can affect the effectiveness of your post-exposure prophylaxis.

1. Lack of Adherence

Proper adherence is the core value in any effective PEP. Some due to the shock of rape or needle prick may be in a hurry to go for a PEP which should not be all that guarantees effective prevention.

The success depends solely on the patient to be able to take the drug when due for the complete 28 days. Apart from that, the fear of the side effects of the PEP may be an obstacle to effective adherence.

2. The type of regimen design

Regimen design in PEP is patient-specific, meaning, what works for Mr. A may not work for Mr. B. The caregiver is to make sure that proper information is taken from the exposed.

3. Inaccurate data from the nature of the risk

When you have minute data with regards to the level of exposure from the source, the viral suppression level and the type of regimen design the source is on (if positive) will help to determine the nature of help to be given to the exposed.

4. Lifestyle of the victim

Initiating a PEP is not a problem, the main problem is to be able to prevent further exposure. This is to avoid getting a resistant strain of the virus.

Therefore, limit the number of sexual partners and all forms of risks of getting infected while on PEP.

5. Unavailability of a working PEP clinic

Post-exposure prophylaxis is an emergency that requires initiation within the first 72 hours. When a PEP clinic is not working or unavailable, it poses a greater risk to the person that wants PEP.

Also, poor monitoring and resolution of side effects that may arise from the PEP will go a long way to help the individuals to adhere to medication

6. Poor counseling of the victim

Most times the victims lack the proper information from the clinic like who to talk to when there is a question to ask, how and when to take drugs e.t.c.

Therefore, the health care provider must make sure that the victim is properly informed about PEP and how it works.

There are other reasons which may not be available in this post. Therefore, you should visit a PEP counselor to help you address some of the questions that will help guarantee effective post-exposure prophylaxis.


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