CHINA: Where’d Antibody Go? 2–3 Months After COVID-19 Infection in asymptomatic and symptomatic patients…

Evidence is coming in from the World Health Organization (WHO) that those who have antibodies to SARS-CoV-2(the virus that causes COVID-19), might not even keep them after 2–3 months.

Researchers in the Wanzhou district of China found that this was especially evident in people who were asymptomatic carriers of SARS-CoV-2. An asymptomatic carrier is someone who carries a disease but does not display its symptoms. They may or may not still be infectious (the safe side is to assume that they are still contagious, and practice good social distancing guidelines set by the Center for Disease Control (CDC).

However, there were two fundamental flaws other researchers and I noticed from this study. More on that shortly. This article was published in Nature Medicine. I took the liberty of hyperlinking it in the journal’s name for any readers interested in reading more on the study.

In the research, the scientists observed a total of 74 people in the Wanzhou district of China. Thirty-seven of these people had no symptoms of COVID-19, whereas the other 37 had symptoms. Their blood was tested before the study to confirm they had COVID-19. After they recovered, about 8 weeks after the COVID infection, the antibodies were undetectable in 40% in the asymptomatic patient population. Antibodies were undetectable in 13% of those who had COVID-19 symptoms [not asymptomatic like the other group].

Research Flaws:

1. Study Design: Because this was a retrospective cohort study, it was after-the-fact and isn’t as up-to-par as a double-blinded clinical trial that vaccines or drugs like hydroxychloroquine.

2. Small sample size: Many studies use sample sizes with hundreds to thousands of research participants to mitigate skewed results brought on by random variance in the population. Meaning, not everyone’s biology and biochemistry are the same, therefore this randomness can create mixed results in the data. By the law of large numbers, a larger quantity of participants is more accurate in results versus a small quantity of research participants.

3. Understanding of our Immune Systems: a major part of the immune system is to “remember” pathogens for future use. It is more efficient for immune cells (Memory B-Cells) to store an immune response inside their DNA versus always sparking an immune response in anticipation of a fight with germs. Helper T-Cells designed to look for specific antigens (a type of signature or surface marker that is unique to viruses and bacteria) find the pathogen inside the body, it then takes that pathogen’s “signature” and hands it over to the B-Cell, which produces antibodies (those Y-Shaped proteins) that will mobilize a much larger immune response and attach to any pathogens with those antibodies.

a. This is especially true for disease states such as autoimmunity, where the body’s immune system overdoes the immune response, leading to damaging the person more than helping them.

4. Immunoglobulin G and M: are antibodies that can be checked for infection. IgG takes years to build up inside the body and therefore would be a better representative of long-term immunity. However, within 8 weeks, IgG dropped by a median of 71% in the asymptomatic group. It dropped 76% in the symptomatic group!

What Now?

Now we need a larger sample size and to look at this more closely. Another thing we can do is do this same experiment in lab animals and see if they have antibodies produced and for how long. Because they are animals, there is less ethnical concern for their treatment versus human beings (it is unethical to infect someone with COVID-19).

So: change the type of study to a double-blinded controlled multicenter study, increase the sample size and also vary the geographic location of the individuals to account for geographic/phenotypic variances, and study how the immune system responds to COVID-19 in both asymptomatic and symptomatic groups of patients.


Long, Q.-X., Tang, X.-J., Shi, Q.-L., Li, Q., Deng, H.-J., Yuan, J., Hu, J.-L., Xu, W., Zhang, Y., Lv, F.-J., Su, K., Zhang, F., Gong, J., Wu, B., Liu, X.-M., Li, J.-J., Qiu, J.-F., Chen, J., & Huang, A.-L. (2020). Clinical and immunological assessment of asymptomatic SARS-CoV-2 infections. Nature Medicine, 1–5.



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Michael Tran

Michael Tran

Writer of sorts. Molecular Biology, Genetics, and English LIterature background. Check out my TikTok! @moleculardrugs