Question
How quickly does viral load drop on treatment?
5 July 2020. Related: All topics, CD4 and viral load, Starting 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.
Hi, my viral load was undetectable but now it increased to 200 but I think the cause of it was stress.Can it drops again since I’m taking my medication accordingly
Hi Xoli,
If you’ve been talking meds for a year and your viral load is still high this means that your meds are’t working. You’re going to need to talk to your doctor about this as it sounds like you need to change combination. There’s more about this here: http://i-base.info/guides/changing
I took my meds every day it been a year now but my viral load is high, what can I do?
Hi Louis,
It doesn’t matter what ARVs a person takes, they all do the same thing, control a persons HIV. If your last viral load test was 3 months ago and it was 115, then yes it should now be less than 50. To know for sure you’d need to have a viral load test.
If my viral load 3 months ago was 115. Is it possible that I’m undetectable now if I’m taking Biktarvy?
Hi Josr,
Your viral load, though not less than 50 is still OK. It going form 45 to 58 could simple be due to the sensitivity of the machine.
last year my doctor changed my meds from ATRIPLA to BIKTARVY. my first test was 450 cd4 with 45 copies for my viral load. 4 months later my test showed an increase in cd4 to 500 with viral load also increase to 58 copies ml. is this normal and nothing to be concerned about. tnx.
Hi Nicky,
It should be as you’ve been on medication for a while.
My viral load was 346 copies last year in July does that mean it might be undetectable this year in july
Hi Eddie,
When a person stops taking medication for more than a week, their viral load rebounds. As you were off meds for a month, your viral load would have rebounded. It’s great that you restarted, however the best thing to do is to talk to your doctor. Let them know that you missed a month. They should check your viral load as it’s important to know if your meds are working.