Q and A

Question

How quickly does viral load drop on treatment?

I’ve been trying to understand on average, the daily rate of decrease in viral load following initial treatment.

I’m guessing that this changes over time and varies from case to case according to the chosen treatment, CD4 count and viral load level and possibly other factors.

However, supposing that the viral load is around 100,000, the CD4 count is around 400 and the treatment used is Atripla, could anyone please let me know the expected % decrease of viral load level per day at least within the 1st month of treatment?

Thank you for the help.

Answer

All HIV combinations (ART) starts working from the first dose.

Viral load is usually reduced by 90% (also referred to as 1 log) within the first few days. It then continues to fall but not as quickly (see below) until it becomes undetectable.

A log is a number mulitplied to the power of 10. So with a viral load of 100,000 copies/mL, a 1-log reduction would bring your viral load down to 10,000 copies/mL and a 3-log reduction would reduce it to 100 copies/mL. (See this factsheet).

You are right that individual factors will lead to difference rates of viral load reductions. These include:

  • How high your viral load was when you start ART.
  • The medicines in the combination (integrase inhibitors casuing the fastest drops).
  • The drug levels of this meds (related to adherence and how they absorb and processes drugs).
  • Good adherence – not missing doses.

UK and US guidelines recommend that your viral load should be undetectable within three months. However, many people achieve this within the first month, especailly if they are using an integrase inhibitor.

Some people take longer, especially if their viral load is very high when they start treatment.

Lots of studies have reported detailed early responses ART, including for efavirenz-based combinations like Atripla.

This decline is often referred to as having three main phases.

The first phase is very rapid – referred to in some studies as being the first few days and in others as within the first two weeks. This is where the actively infected CD4 cells are targeted. CD4 cells infected with HIV only live for a few days and when you start treatment this virus and these cells are quickly reduced.

This results in a viral load drop of perhaps 99% (2 logs) within two weeks.

The second phase, out to the first month is slower, as it is working on cells that live longer. This can easily reduce viral by another 90% (another 1 log reduction). In people with very high viral loads when they start treatment, this second phase may continue for longer until viral load becomes undetectable.

Some researchers also talk about a third phase decline which occurs even more slowly and gradually once your viral load is undetectable.

This relates to a reduction in the levels of infected CD4 cells that are latent (or resting). This pool of cells only slowly decreases over time.

This link is to an early study describing the two-phase viral load reductions.

This answer was updated in July 2020 from a question first posted on 15 September 2012.

299 comments

  1. Chidi

    …And these side effects, does it have any negative effect or after damage to the liver? Just want to make sure.
    What are the damages done after some side effects occur. Bearing in mind side effects could range from 0-10? Just curious pls

  2. Chidi

    Thank you very much for ur swift reaponse. I appreciate it.

  3. Simon Collins

    Hi Chidi, food is okay, just not food with a lot of fat. High fat food will increase efavirenz levels and thee riskd of efavirenz side effects.

  4. Chidi

    What happens if I take my meds immediately or 3o minutes after eating. I’m on efavirenz 600mg, lamivudine 300mg and tenofovir 300mg

  5. Simon Collins

    Hi Chidi, this is a very widely used combination. How long it take to become undetectable depends on how high your viral load was when you started. For some people this happens within the first month, but with this combination most people take 2-3 months.

  6. Chidi

    I am on a combination of efavirenz 600 mg + lamivudine 300 mg + tenofovir 300 mg. How long is it going to take me to become undetectable. I’m in a low budget country (Nigeria). I just want to make sure. This is my 10th day of taking it very carefully and not missing doses.

  7. Roy Trevelion

    Your CD4 and Viral Load (VL) are the main blood tests used to monitor HIV.

    Your CD4 count tells you about your immune system. CD4 cells are produced by the body to help fight infections. The range for HIV negative adults is from about 400 to 1600.

    The VL test shows how much virus is in a small sample of blood. HIV treatment (ART) helps get HIV to undetectable levels, which is under 50 copies.

    You can find more information here.

  8. Brian

    I Want To Know The Difference Between CD4 Count and Viral Load

  9. Simon Collins

    Hi Latoya

    Everyone on HIV treatment should have monitoring tests t check how well the treatment is working. This should usually include your CD4 count. In the UK this is tested one month after starting treatment, but this can also depend on which country you live in.

    As you have been on treatment now for more than a year, your CD4 count should be higher, so please get this checked.

    This will also depend on how low your CD4 count was when you started treatment, but most people get a good response.

  10. Latoya

    Chunky,

    I have been taking a combo of lamivudine/zidovudine 150mg/300mg and nevirapine 200mg since December 2012. Should I see a drastic positive change in my numbers by now? Just don’t want to get my hopes up and when I go for my testing get a huge disappointment cause I am trying to get pregnant.

Comment

Your email address will not be published. Required fields are marked *