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 Niki, if your viral load was only 1500, this probably became undetectable by late August or September. This partly depends on the meds in your combination. When will the doctor test the viral load agains?
Hi – So i was diagnosed with HIV in July 2024, and my viral load was 1500 and my CD4 was 349. I immediately started treatment. What are the chances that my viral load has dropped
Hi Zama, thanks. However high your viral load was in July, guidelines say that nearly everyone will be undetectable within 6 months. This is based on using TLD – tenofovir/lamivudine/dolutegravir.
There is a table at this link that converts viral load log to numbers:
https://i-base.info/qa/factsheets/viral-load-converting-log-values-to-numbers
4.5 log is about 31,000 copies/mL. This is low enough for your viral load to have maybe become undetectable within the frist 1 or 2 months.
Hi, my viral load was 4.5 log when I started ARVs in July 2024, do you think my viral load will be undetectable by November
Hello Alexander and thank you for the question.
If someone living with HIV is on effective treatment then they cannot pass it on to their sexual partners.
Please see here for more information:
https://i-base.info/u-equals-u/
If you are worried, it is always good practice to get tested:
https://i-base.info/guides/testing
Hi. I had one round sex without a condom and I don’t know if I’m infected or not. But the person is now 3 yrs treatment.
Hi Tanner, it i likely you are still undetectable. It is good that you are going to restart now.
You don’t say your country but this sounds like the US because I know the insurance-based care there can be very difficult.
It is shocking that anyone let your meds run out without giving you continued treatment until this was sorted out.
I’ve been HIV undetectable for 10 years. Recently I had an issue with health insurance and was without Genvoya for about 20 days, but today I was able to start again. What is the likelihood that my viral load has rebounded?
Hi Judas, thanks for your question. So long as your viral load is undetectable, your meds will also protect your boyfriend, even if you are not using condoms. Different countries test viral load at different times, but most modern HIV drugs bring viral load to undetectable within 1-3 months.