Poll: Are COVID-19 antibody tests useful?

A new study reported that antibodies decrease within 2-3 months after initial infection and instigated the notion that immunity against SARS-CoV-2 is short term (Quan-Xin Long et al., 2020). It was then widely interpreted that COVID-19 antibody tests are useless, and herd immunity will be impossible. However, an article shared by MolecularCloud scientist questioned this notion and analyzed why herd immunity can still work. What does he say? Read the full article.

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Do you think COVID-19 antibody testing is useful?

503 participants, 31 days left

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10 Reply

I think they could be used for diagnosis alongside PCR based tests, but for epidemiology, a retrospective analysis of places hit early on might generate a better model of the extent of infection.


There is now an increased tendency to use rapid antigen tests because they are much faster and cheaper as compared to RT-PCR even though that remains an ultimate gold standard test for detecting Covid-19 infection.The results of Oxford University's Covid-19 vaccine early human trials (Phase 1 and 2 )looks promising.It shows the Covid vaccine to be safe and capable of inducing an immune response.Once the trials are over successfully and the vaccine is approved,one can manufacture them for use in several countries.


There is now an increased tendency to use rapid antigen tests because they are much faster and cheaper as compared to RT-PCR even though that remains an ultimate gold standard test for detecting Covid-19 infection.The results of Oxford University's Covid-19 vaccine early human trials (Phase 1 and 2 )looks promising.It shows the ovid vaccine to be safe and capable of inducing an immune response.Once the trials are over successfully and the vaccine is approved,one can manufacture them for use in several countries.


An antibody test clearly explains that you had the pathogen (virus) infection at some point in the past. They have been generated in your body to fight against infection. It could be gone, or you could still be contagious. In this test we take a bit of blood sample, like through a finger prick. The test looks for one or both kinds of antibodies to SARS-CoV-2, the virus that causes COVID-19: 1. IgM antibodies, which happen early in an infection 2. IgG antibodies, which are more likely to show up later Most people have IgG antibodies about 14 days after symptoms start. Generally these antibodies stay in blood long after the infection goes away. But due less knowledge we don’t know how long these antibodies stay in body after the new coronavirus infection.


It is definitely useful regardless of the length of antibody-mediated immunity. It can show the population immunity at a specific point of time, and individually it tells whether a person may be protected for infection for a certain period.


This question is incomplete. Useful for what? This requires context. Are they useful somewhere? sure, yes. Are they useful as, say, the only determinants of epidemiological data and resultant public policy? No, of course not. As to the question of antibodies and resistance to infection (which is implied but not really part of the question) - I just do not think we know yet so there is no answer to this. But we await eagerly to know.


Yet in answering, we are enlightened by your explication. So, thanks.

COVID-19 antibody tests check your blood by looking for SARS-CoV-2 antibodies, which may tell you if you had a past infection with the virus. In that respect, the tests at least can help us for diagnosis and are useful in epidemiological investigation.


A lot of people hear these terms, such as “herd immunity” and “vaccine” over and over again, but do not understand how it actually works. Our immunity systems are robust and have “memories”. I would not be surprised to see the antibody level declines over time. Obviously, when the “enemy” is gone, our bodies do not need to keep a large “army”. We only need to keep a small group of “clone troopers” who know how to fight a specific type of enemy and can simply clone more when the same enemies are back. And don’t forget the “special force” such as neutralizing antibodies. A tiny amount of neutralizing antibodies can stop the invasion and further replication of the viruses, and they reside in long-lived plasma cells (LLPC) for quite long, while the majority of biding antibodies fade away. I still believe “herd immunity” will work, but in a systematic way with the assistance of serology tests, especially those that detect neutralizing antibodies.


Why I feel Antibody tests are not useful: Firstly, We know that the antibodies for the SARS-CoV-2 last only for about 2-3 months. Antibodies most commonly are detectable 1-3 weeks after symptom onset, at which time evidence suggests that infectiousness likely is greatly decreased So from this we can know: 1. These antibodies are only temporary. 2. Even if you recover from COVID-19 you’ll have these antibodies. Other limitations: 3. False-positive results are higher (False positive - Even if you are not affected by COVID-19, Your antibody test results may come positive. ) 4. Cross-reactivity - These tests also identify antibodies for other coronaviruses(Like common cold). Given the above limitation, I think other accurate and more reliable tests like RT-PCR can be adopted.


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