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With proper adherence, antiretroviral treatment (ART also called antiretrovirals or ARVs) can reduce HIV to such low levels that the virus can no longer be detected in normal blood tests. This is called having an ‘undetectable’ viral load.   

People with undetectable viral loads can’t pass HIV on through sex. This is also known as undetectable = untransmittable (U=U). 

To know if you are undetectable, you must have your viral load monitored regularly by a health professional.  

Remember your viral load can change. If you stop taking your treatment properly your viral load will go up again.

What is a viral load?

Your viral load is the amount of HIV virus in your body. It is measured by a blood test. 

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What is an undetectable viral load?

When your viral load is so low that blood tests can’t measure it. This is a really good thing! It means your HIV treatment is stopping HIV from making copies of itself and spreading in your body. And it means you can’t pass on HIV! 

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Do I still have HIV if I’m undetectable?

Yes, you still have HIV – it does not mean your HIV is cured. There is still HIV in your body, although it has been reduced to very small amounts by the HIV treatment. 

How will I know if I am undetectable?

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By regular viral load monitoring. This is a blood test to measure how many particles of HIV there are in a small sample of your blood. If your viral load is under 200 copies per millilitre, you’re considered virally suppressed and unable to pass HIV on. 

How long will it take to become undetectable?

Most people who adhere to their treatment become undetectable after about six months. It’s important to have a viral load test to confirm this. 

How often should I test my viral load?

The World Health Organization recommends that you should have your viral load measured after the first six months of treatment and again at 12 months. After becoming undetectable you should still have a viral load test at least every 12 months.  

Do I have to take HIV treatment if my viral load is undetectable?

Yes. It is the HIV treatment that will keep your viral load undetectable. If you stop taking treatment, your viral load will increase – affecting your health and making HIV transmittable again. 

Do I still need to use condoms if I’m undetectable?

Although there’s no HIV risk, being undetectable doesn’t prevent you from getting or passing on other sexually transmitted infections (STIs) or stop unwanted pregnancies. You will have to use other measures such as condoms or contraception to avoid these. If your partner is HIV-negative they may consider using PrEP which is a treatment taken before exposure to HIV to prevent infection. 

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Can my viral load change?

Yes. But it is relatively uncommon if you adhere properly to your medication and are otherwise in good health. Regular viral load monitoring will help you stay on top of any changes. 

What will being undetectable mean for me?

It means that your treatment is controlling HIV in your body. This will protect your immune system and help you to stay in good health. It means that you don’t have to worry about passing HIV onto your sexual partners.  

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What is U=U?

This stands for undetectable equals untransmittable. It means that people with HIV who have an undetectable viral load cannot pass HIV on through sex. 

Can everyone with HIV achieve an undetectable viral load?

Although being virally suppressed and undetectable is the aim of HIV treatment for everyone, there are some reasons why some people can’t achieve an undetectable viral load. These can include factors outside of someone’s control, for example: 

  • drug interactions 

  • side effects 

  • adherence challenges 

  • drug resistance 

  • other health issues. 

For some people, it might be tricky to find a treatment regime that agrees with them. While in some places, viral load testing may not always be available. 

If this is the case for you, it’s essential that you still take your medication exactly as prescribed. Keep regular appointments with your healthcare team. While you may not be ‘undetectable’, you can still remain healthy. Your healthcare workers will work with you to help you have the best treatment outcomes possible. 

Does being undetectable mean you can’t pass HIV on through pregnancy, breastfeeding or sharing injecting equipment?

At the moment we cannot say that there is zero risk of transmitting HIV through pregnancy, breastfeeding or sharing injecting equipment for people with undetectable viral loads. The evidence we have for U=U only applies to sexual transmission currently. 

Although we know that having an undetectable viral load will reduce the risk of passing HIV on by any route, it’s likely that for injecting drugs and breastfeeding the risk will not be zero. 

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