Three broad categories of tests are commonly used to detect coronavirus.
Two among these diagnose whether you have an active infection and a third indicates if you previously had the virus, reports AP.Here’s how they work:
Most tests look for bits of the virus’ genetic material, and require a nasal swab that is taken by a health professional and then sent to a lab.
This is considered the most accurate way to diagnose an infection, but it's not perfect.
The swab has to get a good enough sample so any virus can be detected.
These tests usually take hours at the lab and the results take at least a day, though a handful of rapid tests take about 15 minutes on site.Other genetic tests use saliva, instead of a swab.
Bangladesh RT-PCR Test, a real-time reverse transcription polymerase chain reaction (rRT-PCR) test, to detect Covid-19.
A newer type of test looks for proteins found on the surface of the coronavirus, rather than the virus itself.
These antigen tests are just hitting the market, and experts hope they'll help expand testing and speed up results.
Antigen tests aren't as accurate as genetic tests, but are cheaper, faster and require less specialised laboratory equipment. They still require a nasal swab by a health professional.
Rapid antigen tests perform best when the person is tested in the early stages of infection with SARS-CoV-2 when viral load is generally highest, CDC says.
Bangladesh on Monday announced allowing antigen tests to detect Covid-19.
Antibody tests look for proteins that the body makes to fight off infections in a patient's blood sample.
Antibodies are a sign that a person previously had Covid-19.
Scientists don’t yet know if antibodies protect people from another infection, or how long that protection might last. So antibody tests are mostly useful for researchers measuring what portion of the population was infected.