What are the different types of Covid-19 test?

There are two different strands of testing - one is to find out if a person currently has the disease, and the other determines if they have had it and have built up antibodies, PCR testing and antigen testing are different methods, but both ascertain whe

PCR TEST

Polymerase Chain Reaction (PCR) testing is the most common and is 99% effective. A swab is used to collect an RNA sample (the nucleic acid that converts DNA into proteins) from the patient’s tonsils and inside their nose. RNA is collected as it carries the genetic information of this specific virus. This is then sent to a laboratory where the sample is heated and cooled so it multiplies into larger quantities of DNA. Bioscientists can then see whether the SARS-CoV-2 virus (the virus that causes Covid-19) is present. PCR test results take about two days.

NO-SWAB SALIVA TEST

Patients can do this test at home by collecting about two millimetres of saliva into a sample pot, then sending it off to a laboratory. The sample gets tested using LAMP technology in a lab and the result is then texted to the person. It still takes about 48 hours but there is no need for a patient to leave their home or stick a swab down their throat or up their nose.

ANTIGEN TESTING

These tests look for antigens - proteins produced by the body when it recognises a foreign structure. Antigens can easily be detected in saliva and laboratory testing is not necessary, so can be done in places such as care homes and without a medical professional. Results can be provided more quickly than PCR tests, with some systems already available and dozens more being developed.

90-MINUTE PCR TEST

Machines deliver on-the-spot genetic testing and collect RNA for PCR testing. The RNA, taken using swab samples placed into a cartridge, is inserted into the machine which carries out a PCR test. A successful pilot test across eight London hospitals using British start-up DnaNudge’s machines is being rolled out to urgent NHS patient care and elective surgery settings UK-wide.

LATERAL FLOW TESTING

These tests identify asymptomatic people and will be used for mass testing in England. A swab is inserted into the nose or throat, then the sample is inserted into a tube of liquid which extracts the molecule that determines if Covid-19 is present. Within 15 minutes, the strip of paper will show up with two lines if it is positive, one line on the top if it is negative or one line on the bottom if the test is invalid.

LAMP TESTING

Loop-mediated Isothermal Amplification (LAMP) is a similar process to PCR but produces more viral RNA copies at a constant temperature so can have a result quicker - within a couple of hours or even faster. A swab is used to take samples from the nose or throat, or mucus from hard coughing. The samples are then placed in vials of reagents, then heated in a special machine for 20 minutes.

20-SECOND TEST

The Virolens system uses a portable machine which creates a microscopic holographic image to detect the virus in saliva samples in 20 seconds. Developed by British companies iAbra and TT Electronics, it uses a digital camera attached to a microscope, which then runs data through a computer that can identify the virus from other cells. The device has been trialled at Heathrow Airport

ANTIBODY TEST

Antibody testing looks at whether your body has produced any antibodies to fight against the virus. A blood test is taken from a person who has had Covid-19 symptoms that have disappeared three to four weeks before. A lab test then takes a unique protein the virus makes and tests whether any antibodies in the blood bind to that protein. There are pin-prick tests that are in development.