Undetectable: protection through treatment

How does the protection work? 

HIV drugs prevent the virus from replicating in the body of a person with HIV. With effective treatment, HIV is no longer detectable in the blood after some time. This is referred to as a “viral load below the detection limit”. If the virus is undetectable, it is also not transmissible – this is also referred to as undetectable = untransmittable (U=U).

Shortly thereafter, no or very little HI virus can be detected in semen, vaginal fluid, other body fluids and mucous membranes. It is not possible to transmit HIV at that point.

When are you no longer contagious? 

The following conditions must all be met in order to no longer be contagious:

• The viral load must have been below the detection limit for at least half a year (six months) and the HIV drugs are taken correctly. HIV protection through treatment is not impaired if a tablet is missed once. However, if it occurs more frequently, protection is no longer guaranteed.
• The blood values are checked by a doctor every six months at the latest. This also involves checking the viral load and thus the effectiveness of the HIV drugs.
• The virus is no longer detectable in the blood. This does not mean that there is no more virus in the blood. But the viral load is so low that transmission of HIV is no longer possible.

How reliable is the protection? 

Studies have shown that effective HIV treatment protects against the transmission of HIV as reliably as condoms.

Can you become contagious again? 

If the medication is not taken correctly, the viral load can rise again – and with it the possibility of transmission. However, forgetting to take the medication once does not lead to an increase in the viral load. The medication does not have to be taken at exactly the right time.

In very rare cases, the efficacy of treatment may decrease after a certain period of time for other reasons. However, this does not usually happen quickly. Anyone who regularly gets a medical check-up will detect such changes in good time before the protection provided by the treatment diminishes and can adjust the medication as necessary.

What viral load is considered U=U (undetectable=untransmittable)? 

Viral load is the amount of virus in the blood. The number of virus copies per millilitre of blood plasma is measured. This can be used to calculate the rate at which the HIV is multiplying and whether it can be transmitted. A value of less than 50 copies/ml is regarded as undetectable. Undetectable also means untransmittable. However, not all people living with HIV reach this level with treatment. Suppression of the virus is nevertheless still successful: a viral load of up to 1,000 copies/ml is considered suppressed. There is virtually no risk of sexual transmission of HIV up to the level of 1,000 copies/ml. More information can be found in the WHO document (English).

Can the viral load increase if the person living with HIV has another sexually transmitted infection (STI)? 

That is possible. However, the increase will only be minimal in view of the treatments, so HIV transmission remains almost impossible.

What does undetectable mean for me?