Treatment brings your viral load down very fast. ARVs starts working in the body within the first few days of starting treatment.
UK and US guidelines recommend that your viral load should be undetectable within 3 months. However, many people achieve this within the first month. A few people take longer, especially if their viral load is very high when they start treatment.
A log is a number mulitplied to the power of 10. So with a viral load of 100,000 copies/mL, a 3-log reduction would bring your viral load down to 100 copies/mL. A 4-log reduction to 10 copies/mL. (See this factsheet).
You are right that individual factors will lead to difference rates of viral load reductions. These include:
– your CD4 and viral load results
– the medicines in the combination, and
– the drug levels of this meds (related to adherence and how they absorb and processes drugs).
However, there are lost of studies about the detailed early response to treatment, 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 a study from 2006 in people using efavirenz-based combinations. It reports an average viral load reduction of -1.9 logs after only 10 days on treatment.
This link is to an early study describing the two-phase viral load reductions.
Information on this website is provided by treatment advocates and offered as a guide only. Decisions about your treatment should always be taken in consultation with your doctor.