A new antibody test is trending in the market. This antibody test is done in people to know if they have developed powerful immunity to fight against corona. We all know that corona is a deadly virus that is spreading among humans. However, you should know the fact that there are chances that the test may give false-positive results.
Several companies have rapidly developed several tests after the emergence of SARS-CoV-2. It is the virus that causes COVID-19 in humans. The tests are developed to detect the antibodies that a human body develops against the virus. Several tests are held to detect the virus in the body. But, these tests are a bit different.
The antibodies tests help to check whether someone has already had the infection, and they have formulated the immunity to it. However, it doesn’t necessarily mean that a past infection will confer strong immunity to fight future infections. There are still concerns about it. Additionally, several people may also test positive, if they have encountered other coronaviruses. A few other coronaviruses are available that cause the common cold.
A team of researchers from the University of North California believe that some people have antibodies to fight against other Coronaviruses. These people with other antibodies may receive false-positive results. It means that the result will show they have antibodies developed, but it is to fight another Coronavirus.
This problem arises because coronaviruses generally have several features in common. They particularly have common sequences in their spike proteins. This problem is resolved by the researchers to a great extent. An antibody test is developed that will successfully detect the feature that is unique to only SARS coronaviruses. This way, the test will not detect common coronaviruses, and will only detect what it is meant to do.
Researchers are continuously warning people in the papers, from relying on the screening tests that are not appropriate. They are not giving 100% appropriate results and have low specificity. Problems are encountered in the market in the test that is rushing. It will lead to exacerbating the widespread use of antibody tests that are not accurate.
Researchers have developed more accurate antibody tests by using the spike of the virus, which is known as the receptor-binding domain (RBD). This is believed to bind to a specific protein in the cells of humans, and hence, infect them.
RBDs are believed to vary considerably in distinct coronaviruses. The RBD of SARS CoV-2 is only found similar to the RBD of SARS CoV-1, that caused the SARS outbreak of 2002-2004.
The immune system of humans is expected to generate a lot of antibodies to fight and bind the different parts of a virus. Moreover, only some antibodies produced have the capability of neutralizing it.
Hence, the researchers tried to conduct the antibody test in a different way. They tested whether their assay reflected the number of antibodies that have the capability of neutralizing in the blood samples from patients. This is a significant measure that can make the antibody test more worthy. This is because the concentration of neutralizing antibodies is assessed in the time period of 3 days.
Working with a live virus necessarily requires a high-containment facility. Hence, the assessment is made impractical for the purpose of screening. The team also found that the new RBD based tests showed results that are correlated powerfully with the levels of antibodies that neutralize antibodies present in the blood samples.
It is suggested that this test can help in screening the blood of people who have already recovered from the infection caused by SARS CoV-2 virus. This is basically done to determine whether the blood can be used to treat other patients. This procedure is known as convalescent plasma therapy.
A professor of microbiology and immunology said that a powerful correlation was observed in the levels of RBD binding antibodies and the neutralizing antibodies of SARS CoV-2. It means that the test is not only adequate to identify the people exposed to SARS CoV-2, but it can also identify the level antibodies that neutralize. It will also help to identify a person who can be a potential donor for plasma therapy.
The professor also stated that the entire team is working hard to streamline the entire test procedure. In this way, they can get results in just 70 minutes rather than the long 4-5 hours that it is currently taking.
It is hoped by the researchers that their tests can also detect people whose immune systems have already fought with the virus. Also, people who have developed a few symptoms. Currently, the tests that are available are insufficiently sensitive to come up with valid results for it.
Effective results will work by being a deciding factor to check whether the human population has developed “herd immunity”. After this, they can think about easing lockdown a bit further.
Antibody Test Requires More Work
A most significant limitation is acknowledged by the scientists and the researchers. They say that the samples used to carry on the test were of parents who were symptomatic. Rather, some of them were seriously ill. Does the main question arise that will the antibody test work for asymptomatic people?
To confirm that the people who have very few or no symptoms of the infection have developed RBD antibodies in their blood or not, will require more research. It will also need powerful assays to detect it.
After determining this, they will have to work on the next step. The next step will be to find out where the level of antibodies developed in their body correlates with the ability to neutralize the virus from developing a future similar infection.
When reliable assays are developed to test the antibodies and do a population level testing, it will be convenient to obtain spatial data of high resolution. Antibodies are developed in the blood when a human body fights infection such as COVID-19. This is how a person develops immunity against the virus.