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How Effective Is PrEP In Preventing HIV?

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What Is PrEP?

Pre-Exposure Prophylaxis (also known as PrEP) is a very effective anti-HIV medication that protects Human Immunodeficiency (HIV) negative people from getting infected with the virus.

The term “prophylaxis” aka “preventive measure or advanced guard” means a treatment or medication used and designed to preserve health and prevent the spread of HIV disease or an infection.

It is a beneficial treatment tool for HIV-negative people and for those who are at the highest risk of infection. PrEP greatly minimizes the risk of becoming HIV positive.

PrEP strategy is very effective as it involves taking one pill every day, with or without food. It is recommended to take PrEP every day, at the same time, regardless of whether you go for sexual intercourse or not, for effectiveness and greater protection. Daily consumption of PrEP ensures continued protection.

How Effective Is It?

With strict adherence to PrEP treatment, the risk of being infected with HIV can be minimized and reduced by 99%.

The level of protection from HIV infection in rectal secretions and semen provided by PrEP falls to 97% in people taking 4 doses/week and 77% in those taking 2 doses/ week. It is required to strictly adhere to daily PrEP dosing to offer safety and protection from vaginal HIV infection.

A patient adherent to daily PrEP medication, when withdraws from the treatment or forgets to take the pill, the PrEP protection persists for approximately 7 days following the last dose.

Individual blue PrEP pill.

Why Is There a Need to Take PrEP?

Every year, around 50,000 new HIV infections happen in the United States.

Since, there is no vaccine, effective treatment and cure available for this disease, preventive measures are the key.

PrEP is very effective in protecting against HIV when taken every day.

It is even more effective when other prevention tools like condoms are used in combination. Several studies report that with perfect adherence to PrEP, the risk of HIV infection reduces by around 99% in comparison to those who do not take the medicines.

Truvada for PrEP is the only drug approved by FDA to prevent HIV, and is the only effective treatment.

Now you can get the care you need from wherever you are—aka, your couch.

HIV Background 

HIV aka the Human Immunodeficiency Virus, is a type of virus that is passed person to person through the blood stream. Once this virus enters the body, it destroys the white blood cells that fight against any infection. The virus eventually harms the immune system, and increases the risk for certain cancers and serious infections.

In the U.S. nearly, 1.1 million people are infected with HIV, and approximately 14% of them are not even aware of it.

Even after so much awareness, treatments and medications available, an estimated 50,000 new HIV infections are still happening in the U.S. each year. The reason for this shockingly high number, is the effective HIV prevention and treatment are not sufficiently reaching those who could most benefit from them. The gaps are predominantly in the rural and down trodden areas. Some examples of heavily disproportionately affected populations are the south, as well as Latino and African-American populations.

Treatment guidelines from the United States Department of Health and Human Services recommend and advise that people diagnose with HIV infection should immediately consult their health care provider and start taking ART – antiretroviral therapy. This therapy slows the progression of the infection and helps you live a normal and healthy life for many years.

Before PrEP, there was no effective medication for HIV. People had to rely on traditional STI prevention methods, such as using condoms.

Man with a straight face wearing a striped shirt. He is taking PrEP to prevent HIV standing in front of a green wall.

How Does HIV Spread?

HIV is transmitted in the following ways:

Unprotected Sex

If you have unsafe and unprotected oral, anal, or vaginal, sexual intercourse with anyone who is positive for this disease, then you are at the highest risk for HIV transmission. The virus finds its way into the body during sexual intercourse through the penis, vulva, vaginal lining, rectum, and mouth.

Dirty, Non-Sterile Needles and Syringes

HIV is often spread by sharing infected and non-sterile syringes, needles, or drug use equipment with a person who is positive for this disease. You are at high risk of HIV and other infectious diseases, such as hepatitis by sharing needles that are non-sterile.

During Pregnancy or Delivery, or Through Breast-Feeding

Mothers tested positive for HIV can spread and pass the infection on to their babies. Even breastfeeding can also spread the virus from a mom to her baby. Moms who are HIV positive and get treatment for the infection during pregnancy can significantly reduce the risk of infection to their babies.

Infected Blood Transfusions

It is possible to transmit HIV through infected blood transfusions or infected organ transplants, although this type of transmission has become very rare. Blood donations and organ transplants are always very thoroughly screened.

American hospitals and blood banks carry out thorough screening of the blood supply for HIV antibodies. This reduces the risk of virus transmission.

Bite Wounds

HIV can spread if bitten by a person positive for the infection. It is epidemiologically insignificant and rare, but is possible biologically. If the bite opens the skin, and if the saliva is mixed with blood, the transmission takes place. Cases of HIV sero-conversion following bite of a human being suggest that there must be blood in the biter’s mouth and a discontinuity in the body part of the bitten for transmission to occur. It is important to keep in mind that a bite that doesn’t break the skin and there’s no blood oozing out can’t transmit HIV.

HIV/AIDS Cannot Be Transmitted Through:

  • Mosquito bites
  • Telephones
  • Swimming pools
  • Closed mouth kissing
  • Toilet seats
  • Tears, saliva, or sweat that is not mixed with the blood of a person with HIV/AIDS
  • Shaking hands, hugging, sharing toilets, sharing drinking glasses, sharing towels, bedding, and food utensils
PrEP bottle being held up by a hand in front of a rainbow.

What Does HIV Do to the Body?

HIV destructs the CD4+ cells which are critical to your immune system as they help suppress or regulate immune responses. T helper cells (Th cells) or CD4+ cells are the white blood cells that play an important role in the activation of the cells of the innate adaptive immune system. Cytotoxic T cells, and B-lymphocytes. CD4+ cells do not counterbalance infections but rather activate the body’s response to infections. They keep you protected from any infections and common diseases.

HIV weakens the immune system or the natural defense system of the body and causes various impacts.

The Initial Stages of HIV Cause:

  • Flu-like symptoms
  • Fatigue
  • Mouth and genital ulcers
  • Swollen glands
  • Kidney damage
  • Bumpy skin
  • Diarrhea
  • Heart strain
  • Balance and coordination problems
  • Shingles
  • The immune systems under attack
  • Hypertension
  • Respiratory infection
  • Seizures
  • Dementia
  • Anxiety and depression
  • Nephropathy
  • Inflammation of the tongue
  • Sink sores
  • Aches and pains
  • Itchiness


Acquired Immunodeficiency Syndrome, or AIDS, is the final stage of HIV.

At this stage, there is an increased risk of contracting opportunistic infections, because the immune system of the body is extremely damaged and weakened.

The risk of other infections, like a herpes virus called cytomegalovirus, also increases. It can cause problems like sore throat, swollen glands, low appetite, problem in eyes, lungs, and digestive tract.

Cancer of the blood vessel walls termed as Kaposi sarcoma is common in people who are HIV-positive. Symptoms include red or dark purple lesions on the mouth and skin. It can also cause problems in the lungs, digestive tract, and other internal organs.

HIV and AIDS also put you at higher risk of developing lymphomas. Swollen lymph nodes is an early sign of lymphoma.

Some common complications of AIDS include:

  • Impaired memory
  • Confusion and anxiety
  • Depression

Further Complications

Another complication of AIDS is Toxoplasma encephalitis (TE). In people who are HIV/AIDS positive and have a weakened immune system, toxoplasmosis can result in inflammation of the brain and spinal cord, seizures and life-threatening illnesses such as encephalitis, caused by a parasite in cat feces.

People who are HIV positive are at an increased risk of serious medical conditions and complications like salmonellosis disease caused by a group of bacteria called Salmonella.

It spreads through contaminated water and food and triggers vomiting, abdominal discomfort and pain, and diarrhoea. It can also cause infection in joins, bones, urine, blood, or the nervous system (spinal brain and fluid). People with weakened immune system, including HIV positive, are at higher risk of serious complications from this infection in comparison to people with healthy immune systems.

Bottle filled with 30 tablets of PrEP.

In people who are HIV positive, the risk of pulmonary arterial hypertension (PAH) is extremely high. PAH is a life-threatening medical condition which means tiny arteries in your lungs become narrow or blocked due to very high blood pressure. Over time, pulmonary arterial hypertension will impact and strain your heart. HIV increases the risk of flu (influenza causing virus), colds, and pneumonia.

In the absence of HIV preventive treatment, advanced treatment increases the risk for complications like pneumonia, tuberculosis, and a medical condition called PCP – pneumocystis carinii pneumonia. PCP causes trouble breathing, cough, and fever.

How Does PrEP Work?

Pre-Exposure Prophylaxis (known as PrEP) contains 2 antiretroviral drugs that are also used to treat people with HIV:

  • TDF: tenofovir disoproxil fumarate (Brand name Emtriva)
  • FTC: emtricitabine (in combination known as TDF/FTC) also called tenofovir DF (Brand name Viread)

This combination of drugs is called Truvada. These drugs suppress the infection causing virus in people living with the HIV condition. There are other generic forms of the pill available with similar active ingredients.

In terms of HIV prevention, PrEP is another way to prevent the infection just like condoms.

Using safer sex tools and practices, like condoms, in a correct and consistent manner ensures maximum protection against any infection.

But, when these safer sex practices are not used properly and consistently the risk of contracting HIV increases manifold. PrEP, like condoms, cannot safeguard you against HIV if they’re not being used!

PrEP is not a treatment or vaccine against the HIV infection.

Unlike condoms, PrEP does not safeguard you against other STIs – sexually transmissible infections.

When taking PrEP, the drug (in the form of tablet) builds up in your body to the point where it is effective in breaking the replication cycle of HIV. This brings down the probability that it will take hold in your body.

How Long Does It Take to Work?

Building up protective levels of PrEP in your body takes time. Several research studies have reported that maximum safety is achieved after seven days for rectal tissue, however it will take twenty days for full shielding to be achieved in blood and vaginal tissue.

It is recommended to assume that you will not achieve maximum protection until at least 20 days after you start taking PrEP, only if you take it consistently without missing any pills. This is recommended for all people taking PrEP. If you are considering taking On-demand PrEP, please talk to your health provider first.


PrEP is an effective treatment for people who do not have HIV infection, but are at an increased risk of being infected.

The name of the medication used is Truvada. Truvada contains 2 antiviral drugs, TDF (tenofovir disoproxil fumarate) and FTC (emtricitabine).These drugs suppress the virus in people living with an HIV infection.

There is no cure for HIV. However, with proper medical support, HIV infections can be prevented and controlled.

PrEP programs are the most effective treatment available as of now for HIV infection.

PrEP offers standardized procedures for referral, monitoring, reporting, and linkage with regular analysis.

If people who are HIV positive take Truvada for PrEP as prescribed, their viral burden (quantity of HIV in their blood) can become imperceptible. If it stays imperceptible, HIV positive people can lead a normal, long and healthy lives. They also have effectively no risk of transmitting HIV to an HIV-negative partner through sexual activity.


Centers for Disease Control and Prevention. PrEP. Accessed March 12, 2020 at Pre-exposure Prophylaxis (PrEP) for HIV Prevention. Accessed March 12, 2020 at

Harvard Health Publishing. PrEP prevents HIV — so why aren’t more people taking it? Accessed March 12, 2020 at

New Zealand AIDS Foundation. Pre-exposure Prophylaxis (PrEP). Accessed March 12, 2020 at

PrEP The Basics. Accessed March 12, 2020 at

Pharmac. PrEP for HIV prevention: emtricitabine with tenofovir disoproxil fumarate. Accessed March 12, 2020 at

Now you can get the care you need from wherever you are—aka, your couch.

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