Viral Load

Heard of 'viral load'? It means: how much HIV is in the body of someone who has the virus. Viral load can be measured, normally in a blood test. Viral load can be 'high', 'low' or 'undetectable'. If it's 'high' that means:

• more chance that person will get sick
• more chance they'll pass on HIV during unprotected sex

So viral load is linked to how infectious someone is. The lower their viral load, the less likely they might give HIV to others. Viral load (and how infectious blood, cum, etc is) can be very high:

• in the first weeks or months after someone gets HIV (before they probably even realise they have it)
• if their HIV drugs aren't working (or they're not taking any)
• or if they're run down or have another infection, including sexually transmitted ones.

'Undetectable viral load'

'Undetectable viral load' doesn't mean 'no HIV there'. It definitely still is but the test isn't sensitive enough to measure these low levels. Unprotected sex when someone's viral load is 'undetectable' may be safer but it's not safe because:

• there could still be enough virus to infect others
• viral load may have gone up since the last test (it can go up and down over time)
• the tests measure HIV in blood. But levels can be much higher in cum, pre-cum or anal mucus.

• This article was last reviewed on: 18/10/11
• Date due for next review: 18/10/13