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HIV viral load

Viral load is a test that measures how much HIV is present in a drop of blood. After being diagnosed with HIV, viral load testing is regularly done to monitor the level of virus in the body.

The goal of HIV treatment is to reach an “undetectable” viral load. This means that HIV is suppressed to such a low level that the viral load test is not able to detect any virus in the blood. “Undetectable” does not mean that there is no HIV present in the body, but it does mean that there is very little HIV in the blood.

Benefits of a low viral load

Using medications to reach an undetectable viral load is important to keep HIV under control and prevent it from causing health problems.

Taking HIV medication and having an undetectable viral load also significantly lowers the chance of passing HIV to others.  Research has shown that in couples where one person has HIV and the other does not, if the HIV-positive partner is on treatment and has an undetectable viral load, HIV is not passed between partners.

Changes in viral load

In general, if someone is taking their HIV medication regularly, their viral load will remain suppressed.  Certain situations (like acute illness or getting vaccinations) may cause a temporary increase in a person’s viral load.

Viral load “blips” can also happen, which are unexplained temporary viral load increases in a person who normally has an undetectable viral load. These short-term increases usually do not cause any major health impacts.  However, long-term increases in the viral load may lead a health care provider to look at changing a person’s medication.

Undetectable = Untransmittable

A person with an undetectable viral load cannot pass HIV to their sexual partners. 

The Undetectable = Untransmittable (U=U) campaign is a global community of HIV advocates, activists, researchers and community partners promoting the fact that people living with HIV who are on effective treatment do not sexually pass HIV.  The U=U campaign is supported by over 500 organizations worldwide, including the BC Centre for Disease Control, the US Centers for Disease Control, the Canadian AIDS Society and the British Columbia Centre for Excellence in HIV/AIDS.


  • CATIE – Information on viral load testing from Canada’s leading source of HIV information.
  • AIDSmap.org – Comprehensive information on HIV viral load.
  • CATIE.org – Information on U=U from Canada’s leading source of HIV information.
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