2. 9 History of viral load and different cut-offs

Viral load tests changed the way HIV drugs are developed and approved.

They also changed the way that HIV is managed in the clinic.

• The tests proved that HIV steadily progresses after infection.
• For the first ten years, most researchers thought HIV had a latency period lasting several years. They thought something else caused HIV to become symptomatic.
• Several studies also showed that detectable viral load can directly cause serious health complications. This is one reason that ART is recommended when you are first diagnosed. The other is that modern treatment is very safe. It has a very low risk of serious side effects.
• Viral load tests can show within days or even hours whether a drug is active. Before this, researchers only had to wait for months to see CD4 count changes or progression to more complicated infections or deaths.

Viral load tests have also become more sensitive.

• In the 1990s, viral load tests were a new technology being developed as a research tool.
• By 1995, viral load tests had a cut-off of 10,000 copies/mL.
• By 1996-7, tests could measure down to 400 or 500 copies/mL.
• Since 1998, most tests measure down to 200, 50 or 40 copies/mL.
• Research can be even more sensitive, down to 5 or even 1 copy/mL.

However, some countries use tests that cut-off at 1,000 copies/mL. This is where access to viral load is limited and more expensive. This is because WHO guidelines use 1000 copies/mL to decide whether ART is working or if it needs to be changed.

Viral load tests now allow a high level of individual care.

Each person can now have their HIV monitored individually.

Before this, everyone would be treated the same, with a standard treatment. Many researchers (and funders) didn’t think individual monitoring would be possible.

Last updated: 1 January 2023.