What are the issues preventing us to find a high quality antigen rapid test (immunochromatography) against COVID-19
Rapid detection kits are less sensitive we can think ELISA kits which helps to screen large number of samples with good sensitivity and specificity
One type of rapid diagnostic test (RDT) detects the presence of viral proteins (antigens) expressed by the COVID-19 virus in a sample from the respiratory tract of a person. If the target antigen is present in sufficient concentrations in the sample, it will bind to specific antibodies fixed to a paper strip enclosed in a plastic casing and generate a visually detectable signal, typically within 30 minutes. The antigen(s) detected are expressed only when the virus is actively replicating; therefore, such tests are best used to identify acute or early infection.
How well the tests work depends on several factors, including the time from onset of illness, the concentration of virus in the specimen, the quality of the specimen collected from a person and how it is processed, and the precise formulation of the reagents in the test kits. Based on experience with antigen-based RDTs for other respiratory diseases such as influenza, in which affected patients have comparable concentrations of influenza virus in respiratory samples as seen in COVID-19, the sensitivity of these tests might be expected to vary from 34% to 80%.1
Based on this information, half or more of COVID-19 infected patients might be missed by such tests, depending on the group of patients tested. These assumptions urgently require further study to understand whether they are accurate. Additionally, false-positive results – that is, a test showing that a person is infected when they are not – could occur if the antibodies on the test strip also recognize antigens of viruses other than COVID-19, such as from human coronaviruses that cause the common cold. If any of the antigen detection tests that are under development or commercialized demonstrate adequate performance, they could potentially be used as triage tests to rapidly identify patients who are very likely to have COVID-19, reducing or eliminating the need for expensive molecular confirmatory testing.
Research suggest [1, 2] that antigen material should be readily available in serological samples from the onset until the end of infection. Hence, a reliable direct antigen rapid test should be possible to create. In the case you are interested check out my paper on this: Preprint Covid-19 Rapid Test - BLUE PAPER
Of course there are a number of things that could make this really tricky (outlined in my paper), but personally I think, with the right resources, we can solve it.
[1] L. Liu, W. Liu, S. Wang, S. Zheng, et.al, medRxiv 20031856, (2020)
doi: Preprint A preliminary study on serological assay for severe acute re...
[2] S. Khan, R. Nakajima, A. Jain, R. Ramiro de Assis, et.al, BioRxiv 006544, (2020)
doi: Preprint Analysis of Serologic Cross-Reactivity Between Common Human ...
There is no problem, infact developing a rapid test will help in the rapid diagnosis and detection of the suspected cases of COVID-19 and thus help in preventing the rapid transmission of the virus.