After a slight decrease in the first months after infection, the level of antibodies against SARS-CoV-2 remains stable for at least five months.
In response to infection, our immune system begins to synthesize antibodies that help detect and destroy bacteria and viruses. Immune cells construct antibodies – immunoglobulin proteins – so that they recognize the pathogen by its characteristic molecular characteristics, and thanks to specific antibodies, infection can be eliminated quickly and efficiently. But here it is not only the quality of the antibodies themselves that is important, but also the ability of immune cells to synthesize them for a long time. That is, for example, if a person had the flu during the flu season, and immediately after recovery, the immune system forgot how to make antibodies against the influenza virus, then the disease may start again, for example, after a month or a couple of weeks – as soon as the virus flies into organism.
Antibodies that stick around a viral particle. (Illustration: animaxx3d / Depositphotos) –
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It is sometimes said about the new coronavirus SARS-CoV-2 that antibodies to it quickly disappear for some reason, which means there is a high risk of contracting COVID-19coronavirus infection again and again. However, employees Main Sinai Medical Center asserted in an article in Science, that antibodies against SARS-CoV-2 remain with us for a long time – at least for five months. Researchers used data from analyzes of more than 72,000 patients at the medical center, who were admitted to it from March to October. Their blood was tested for antibodies to the virus using an enzyme-linked immunosorbent assay, the essence of which is that antibodies are caught on the viral protein (in this case, on the S-envelope protein of SARS-CoV-2). This method is very sensitive and with it there is little chance of false results, both positive and negative.
The amount of antibodies in patients was determined by diluting the sample for analysis. If the sample was diluted 960 times or more, and antibodies were still detected, this meant that there were many of them. If antibodies were detected at a dilution of no more than 320 times, it means that a person has a moderate amount of antibodies. If antibodies were detected at dilution no more than 80–160 times, then they are few and very few.
Of more than 72 thousand patients tested, antibodies against coronavirus were found in just over 32 thousand. 2.29% had very few antibodies, 4.83% had just a little, 22.29% had a moderate amount of antibodies, and about 70% had high levels. That is, the majority of patients with antibodies against SARS-CoV-2 form a lot.
Another question is how well these antibodies neutralize the virus, because, even when targeted against a specific pathogen, they can poorly bind to it. It turned out that antibodies against the virus effectively neutralize the virus in only half of those patients in whom they are formed a little. In those with moderate antibody levels, antibodies neutralize the virus in 90%. And they work effectively in all patients whose antibody levels are high.
Finally, in some patients, antibody levels were checked three and five months after the onset of symptoms of infection. Those with high levels of antibodies declined slightly by the third month, but remained moderately high in the following months. Those with low or moderate levels of antibodies even became slightly more than at the beginning, and then their concentration in the blood again remained stable. At the beginning of the infection, antibodies synthesized one type of “antibody” cells, then another, but in general, everything happened the same as in other viral infections.
Researchers are going to continue to monitor the level of antibodies in patients with COVID-19 in order to understand how their level will change over a longer period of time. The fact that their concentration remains high enough does not necessarily mean that a person will never get infected again. But, at least, this reduces the likelihood of re-infection, and if it does happen, a high level of antibodies will alleviate the symptoms and help get rid of it quickly.
