Glossary

compensatory mutation – this refer to an additional mutation, usually in the context of the fitness of a virus. For example, the mutations that stop a drug form working often stop the virus from reproducing as well. Additional mutations that return the virus to it’s former fitness are called compensatory mutations. They compensate for the reduced viral fitness. See revertant mutation.

viral rebound – when your viral load has been undetectable (under 50 copies/mL) and then becomes detectable. Sometimes viral rebound can be a lab error, sometimes a small temporary blip, and sometimes a real rebound that shows your virus may have developed resistance to one or more of the drugs in a combination treatment. See: virological failure.

symptom – a sign of illness.

confirmatory test – a second test to double-check the results of a previous one. For example, if your viral load is usually undetectable and then becomes detectable, you need a second confirmatory test. This is to check that the detectable result was not a laboratory error on just a temporary blip.

side effect – an unwanted effect from taking a medicine. Sometimes called an adverse event or drug toxicity.