Follow up on this question.

In the India ICMR guidelines and testing strategy for testing have approved antibody (IgM, IgG)-based rapid test kit , True Nat is a screening test based on reverse transcription polymerase chain reaction (RT-PCR) tests and Cepheid Xpert Xpress SARS-CoV2 is a FDA approved Cartridge Based Nucleic Acid Amplification Test (CBNAAT) for use under an emergency use authorization (EUA) and some pre-screening kits.

https://www.randoxhealth.com/product/coronavirus-covid-19-home-testing-kit/

https://www.dnalegal.com/covid-19-coronavirus-testing-kits

Shivani Raval But, in India, they don't use RT-PCR based screening method at all?

The accuracy of antibody-based screening can be a problem. There are about 70 antibody-based kits flooding the US markets. There were not regulated by the FDA. FDA lets these companies self-validate their products. Quality and accuracy are not guaranteed. However, FDA changes its attitude after complains from scientists, and demands the companies to provide 'accuracy proof' in 10 days, otherwise their products will be removed from the markets. The F.D.A.’s action follows a report by more than 50 scientists, which found that only three out of 14 antibody tests gave consistently reliable results, and even the best had flaws.

Fears of Unregulated 'Wild West' as COVID-19 Blood Tests Hit the U.S. Market (https://time.com/5819737/covid-19-blood-tests/)

Yuan-Yeu Yau Yes prior we have used it. The test kit can detect the virus within three hours by using real time-polymerase chain reaction (Real-Time PCR) is used for qualitative detection of genetic material called nucleic acid (RNA) from Sars-CoV-2, the virus that causes Covid-19, and is the most accurate diagnostic test for infection.Rapid antibody tests are surveillance tools, they are not tools for disease positivity. For diagnosis of Covid-19, we need RT-PCR, and a planned scale-up is happening.

Different kits from different company are available in the world.

Thanks to Shivani Raval ,Huda S. Al-Rawazq , Sadanand Pandey

Just like one collar size does not fit all, different test kits are not for every patient of COVID-19.

The test kits used depend on whether you want to diagnose active COVID-19 infection or just want to know the exposure rate of the populations.

1. RT-PCR based kits test people who are symptomatic or have had a recent contact with a confirmed COVID-19 patient. These test kits use nasopharyngeal, or oropharyngeal swabs. The results are available in 24-48 hours.The chances of such tests to be positive depend on when they are taken. In a symptomatic person they are positive anything from 2 days before symptoms up to 2 weeks, although occasional patients even as they become asymptomatic can remain positive up to 35 days. These kits are for one patient one test and are more expensive. Importantly results vary depending upon the expertise on the personal obtaining the sample.

2. Antibody test kits detect antibodies (IgM early on, IgG later on) against the proteins on surface of the virus, are easily done in large batches (thousands at one time), are inexpensive, need a blood sample, often become positive in 2nd week onward. The test result is available within 30 minutes and does not depend of sample expertise. They are good for screening asymptomatic population to know their exposure rate to COVID-19. However, they may miss out patients if done too early, in first 2 weeks. Tests based on separate IgM or IgG test kits can indicate new or past infection respectively.

Many countries are planning to give an "immunity passport" based on positive antibody tests to let such people work and travel.

However, one has to be careful about the validation the test kits, more so with the antibody tests. If used in the right scenario, at the right time frame, in the right person, one test, s aserial tests (for detecting recovery of a COVID-19 patient).

Remember to separate horses from zebras i.e active infection from old exposure.

Ortho Clinical Diagnostics have developed a Total (including IgM and IgG) and IgG Anti-body test with 100% specificity. This test is among four or so that have received Emergency Use Authorization from the FDA. This is an ELISA Based Antibody test. The time to first result for Total test is 48 minutes with a sample volume of 80uL and the and IgG test is 48 minutes with sample volume of 20uL.

These tests are can be run on VITROS analysers that are widely used in Laboratories globally.

For more information see: https://www.orthoclinicaldiagnostics.com/en-us/home/covid-19-antibody-test-released-by-ortho-clinical-diagnostics

The best diagnostic method is clinical and radiological evaluation. The diagnostic sensitivity of all kits is very low.

HI

Please check the link

https://www.citydoc.org.uk/covid-19-home-testing-kit/

Interesting question that provoked several useful information.