Are the antibodies produced by the vaccine the same after infection with the Corona virus?

Are the antibodies produced by the vaccine the same after infection with the Corona virus?

Used to confirm Covid-19 infection or to measure the level of antibodies that ensure vaccine efficacy Can serology detect a person’s vaccination status? Yes, sometimes!

A serology test is done in a biology lab, which is a blood test that detects the presence of virus-specific antibodies. Unlike antigen or PCR tests, it does not make it possible to make a diagnosis or tell if a person is contagious, since antibodies are formed late, several days after infection. For Covid-19, it was once used primarily to find out if a person had been in contact with SARS-CoV-2.

What is the use of serums?

Today, with vaccination also allowing the development of protective antibodies, serology is finding other indications. This is particularly the case with follow-up of immunocompromised people (for example, those with cancer under chemotherapy, transplantation or dialysis), as Dr. Jerome Barrier, medical oncologist, explained in Nomirama: We know that vaccinating them may be less effective. Therefore, if their antibody level is low, this makes it possible to send reminders of previous and repeated vaccinations (the fourth dose is possible since September in France) ».

He sees some flaws in the method: It is difficult to determine an adequate protection threshold. In addition, due to immune escapeAnd Omicron is a game-changer: this variant requires a higher level of protective antibodies to avoid a symptomatic form. »

Dr. Barrier points out other uses for serology: This analysis may be useful in confirming that a person does indeed have Covid when prolonged Covid is suspected. Positive sera, in intensive care, can also lead to a false health declaration if a serious, inexplicable form is present in the vaccinated person. »

Are the antibodies produced by the vaccine the same after infection with the Corona virus?
We hope Monica does not suffer from Covid. Source: Screenshot from Friends (NBC/Netflix)

Different vaccines for the vaccinated and infected?

Can we distinguish the serum of a vaccinated person from someone previously infected? In some cases, yes. ” It is very variable, with different factors playing a role, such as the time after infection or vaccination. The infection may confer a higher total level of antibodies than would be given after two doses. The level that will be clearly determined thanks to the third dose of the vaccine Dr. Barrier adds.

In fact, if we want to search for the little monster, we can find it. Eric Bailly, researcher in immuno-oncology in Strasbourg and member of the Du Côté de la science group explains: When ELISA tests are performed in vitro, it is possible, in contrast to rapid serological tests (TROD), to distinguish between anti-Surge antibodies (anti-S) and anti-nucleocapsid (anti-N) antibodies. »

Reminder: Spike is the protein that allows SARS-CoV‑2 to enter our cells and determines the nucleocapsid assembly made up of the virus capsid and the viral genome. Infection leads to the formation of anti-nucleocapsids and anti-nucleocapsids, and vaccination produces only anti-nucleocapsids.

Therefore, anti-S will be present in both infected and vaccinated people. On the other hand, anti-N will only be present in people who have developed Covid-19. Thus:

  • People who have been vaccinated but not infected will have anti-S.
  • Previously vaccinated and infected persons will have anti-S and anti-N
  • Unvaccinated and previously infected people will have anti-S and anti-N

It is always possible, especially for diagnostic purposes in the aftermath, to determine if a vaccinated person has previously been infected with SarS-CoV-2. However, antibodies tend to disappear after infection or vaccination. So today it will be difficult to determine whether the fatigue or pain you have been experiencing for two years is related to the prolonged coronavirus infection in February or March 2020 when PCR tests were not available.

Positive sera do not replace vaccination

Finally, it must be selected The presence of antibodies is not sufficient to protect against infection, but its rate can give indications for people at risk, Dr. Barrier points out: “ Unfortunately, antibodies are not necessarily enough to prevent infection. Below a certain anti-elevation threshold after vaccination in a patient with a malignant haematological disease or a transplant, who should be protected by anti-SARS-Cov-2 monoclonal antibody, as a precaution (EVUSHELD). »

In most cases, in people who are not immunocompromised, serology serves only to satisfy a certain curiosity … and cannot replace vaccination.

Leave a Comment

Your email address will not be published.