Rapid tests to detect GAS (bacteria) give a positive or negative result that is usually based on a colour change on a test strip that contains a throat swab (sample). Test strips detect a cell wall carbohydrate that is specific to GAS by using an immunologic reaction. Rapid testing can be performed in the doctors office and usually takes 5–10 minutes for the test strip to indicate the result. Specificity for most rapid tests is approximately 95%, however sensitivity is about 85%. Although the use of rapid testing has been linked with an overall reduction in antibiotic prescriptions, further research is necessary to understand other outcomes such as safety, and when the person starts to feel better.