COVID-19 diagnostic testing can provide information to: (1) Is the patient infected? (2) How bad is the COVID-19 pandemic? (3) What can be done to contain the disease and prevent it from spreading without collapsing the healthcare system? Massive testing can serve to put the pandemic under control by preventing the influx of infected people from outside and containing & mitigating the infection within. Otherwise, a serious measure such as a total city lockdown may have to be taken to be effective.
SARS-CoV-2 nucleic acid test detects nucleic acid segments of the coronavirus. It is a highly specific, technically demanding, and fairly expensive test. When in combination with clinical observations, this test is very useful in the diagnosis of COVID-19. However, due to sampling limitations, restriction, and other unknown reasons, this test tends to miss some samples from infected patients.
Moreover, greater than half of the people who were confirmed to have COVID-19 contracted the virus from someone who didn’t know they had it. Indeed, the infection symptom may take 5 days or longer to be noticed (i.e., long incubation time), and young people tend to appear asymptomatic which may be due to high antibody titer, thus leading to the transmission of the virus by asymptomatic people.
Clearly, clinical observation (checks the symptom) and nucleic acid testing (checks the coronavirus) cannot fully meet the challenge of asymptomatic transmission.
The immune system generates antibodies when our body is invaded by pathogens such as virus. The IgM antibody rises to an adequate level in about 7 days and the IgG antibody rises to a high level in about 14 days. The antibodies can play two roles, it bind pathogens tightly and neutralize them, or it bind pathogens then recruit lymphocytes to kill them.
Therefore, detection of a specific antibody evidences that a person has been infected with a specific virus, regardless of that person is symptomatic or asymptomatic.
The coronavirus antibody diagnostic test is very simple, quick, and inexpensive. Only a small amount of blood sample from a patient, or a person is suspicious of infection, is needed for the testing. First, if the specific antibody detection is positive, this patient should be checked for symptoms and clinical history, and be treated immediately. Second, if the specific antibody detection is negative, it indicates that the patient is either not infected, or is infected but has not been infected for more than 7 days. Therefore, to be safe, this patient can be quarantined (or isolated at home) and observed for any symptom for 14 days, then tested again. If the second test result is again negative, this patient is not infected and free to go; if the second test result is positive, this patient has recent infection and should be treated accordingly. It should be known that the antibody testing in coordination with the nucleic acid testing will provide very useful information.
In so doing, COVID-19 patients with long incubation time and/or is asymptomatic cannot escape the antibody detection, because such detection is based on the nature reactions of immune response to the virus infection. On the other hand, because the nucleic acid testing detects the presence of virus nucleic acid, which is unable to identify patients who are asymptomatic and transmissive, or patients who have virus nucleic acid too low to be detected but still could transmit the disease.
In summary, with information from the nucleic acid testing and clinical observation, the typical quarantine for 14 days is to find out whether one with symptom has been infected with coronavirus, whereas “quarantine for 14 days with additional two antibody testing 14 days apart” is able to identify all infected patient either with or without symptoms. Such information can prevent asymptomatic transmission and also converge the spread of COVID-19 effectively.
Point-of-care coronavirus antibody rapid test is easy to use without instrument. However, it cannot provide quantitative data or process large quantity of sample. High throughput automatic seroscreening for coronavirus antibody detection using the ELISA format can run millions of tests daily nationwide at very low cost. It is useful in assaying everyone in the US who needs the testing, as well as all of the people coming into this country, thus converging the COVID-19 pandemic, reducing the social and economic impacts, and helping us to get back to our normal lives.