- Antigen test a must in 1-7 days of symptoms
- Test can be done in areas where PCR testing unavailable, infection rate high
- Acceptable level of test kits – 80% sensitivity, 97% specificity
- Tests not applicable for asymptomatic individuals, in ports, and areas with low infection rate
If the antigen test for Covid-19 detection on a person comes positive, he or she will be considered 100% Covid-19 positive, and no other test is required in that case, the health ministry has said.
However, if the result of the antigen test is negative, the Covid-19 infection should be confirmed through a Polymerase Chain Reaction (PCR) or Gene Expert test, it also said in its recently issued guidelines.
The guidelines say the antigen test should be done within 1 to 7 days once Covid-19 symptoms develop in a person. This test can be done in areas where PCR testing is not available and where the infection rate is high.
In addition, the guidelines provide for the health ministry's approval for the use of kits in antigen and antibody tests. But the level of antigen test kits, compared to real-time PCR tests, should contain at least 80% sensitivity and 97% specificity. And in the case of antibody tests, the acceptable level of the kit should be at least 90% in sensitivity and 95% in specificity.
According to the guidelines, antigen tests will not apply to airports, land ports and seaports, asymptomatic individuals and areas where the rate of infection is low. Also, this test will not apply to people undergone pre-blood donation tests and patients with elective surgery and symptoms other than Covid-19 (point of care).
The guidelines, undersigned by Dr Bilkis Begum, deputy secretary at the Directorate General of Health Services, state that the antibody test will not be applicable in the case of Covid-19 detection and the point of care.
The Institute of Epidemiology, Disease Control and Research (IEDCR) will act as a reference laboratory to ensure the quality of various laboratory tests used to diagnose Covid-19. The quality of the tests should be verified by sending a certain number of samples to the reference laboratory from time to time, the guidelines add.