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Explained: Could pre-existing antibodies help protect some people against COVID-19? – The Indian Express

Written by
Mehr Gill
, Edited by Explained Desk |

Updated: November 8, 2020 11:46:10 am

A health worker takes a nasal swab sample to test for COVID-19 in Hyderabad. (AP)

Researchers at the Francis Crick Institute and the University College London have found that some antibodies that are created by the immune system during infection with some common cold viruses may help protect against SARS-CoV-2.

Their findings were published in the journal Science on November 6.

What have the researchers found?

In their study, the researchers note that some people, especially children, may have antibodies that are reactive to SARS-CoV-2, even though they may have never been infected with COVID-19. According to the authors of the study, these antibodies were likely formed as a result of exposure to some common cold coronaviruses, which are structurally similar to SARS-CoV-2.

Researchers analysed over 300 blood samples collected between 2011 and 2018, out of which nearly all of them had antibodies that reacted with common cold coronaviruses. Within this pool of samples, about 1 in 20 adults also had antibodies that cross-reacted with SARS-CoV-2. Significantly, researchers found the cross-reactive antibodies were found more frequently in the blood samples taken from children aged between six and 16.

How do cross-reactive antibodies work?

The spike protein of SARS-CoV-2 consists of two subunits, S1 and S2. S1 allows the virus to latch on to cells in the body and is relatively diverse among coronaviruses, S2, on the other hand, is more similar among coronaviruses and lets the virus into cells. This similarity of the S2 subunit in common cold coronaviruses and SARS-CoV-2 could be the reason that these antibodies are able to neutralise the COVID-19 causing virus.

What does this mean?

Since the researchers found higher levels of cross-reactive antibodies among children, it could explain why children are less likely to become severely ill from COVID-19. Even so, there is no evidence yet that the presence of cross-reactive antibodies prevents SARS-CoV-2 or its spread. Therefore, researchers have cautioned that people who have recently had a cold should not think that they are immune to COVID-19. 📣 Express Explained is now on Telegram

Kevin Ng, lead author of the study, was quoted as saying in a press release: “Our results show that children are much more likely to have these cross-reactive antibodies than adults. More research is needed to understand why this is, but it could be down to children being more regularly exposed to other coronaviruses.

Further, more investigation is required to find out exactly how immunity to one coronavirus is modified by exposure to another and why this activity declines with age.


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