Study provides strong evidence of transplacental transfer of IgG antibodies after COVID vaccination

Messenger ribonucleic acids (mRNA) vaccines have been proven to be safe, effective, and fast-acting against the coronavirus infection 2019 (COVID-19). Evidence also suggests that these vaccines are safe for pregnant women to use.

This is despite the fact that 16.3% of pregnant women have not received the vaccine. This is understandable given the media interest in possible adverse effects and the high level of media attention. To help further understand the effects of mRNA vaccines on pregnant women, researchers from New York University have been investigating the transplacental transmission of antibodies in pregnant women who have received the vaccine.

Study found high levels of antibody in the cord blood of pregnant women who had been vaccinated against COVID-19. Image Credit: Marina Demidiuk /

Vaccine approaches

Vaccines are generally composed of attenuated or inactive forms of the virus, which are unable to be infected by cells or reproduce. This allows the immune system to detect specific epitopes and then produce antibodies against them. This method of immunization has proved to be very effective; however, it can lead to some safety issues, as the virus can reactivate or become infected if they acquire characteristics from the wild-type virus.

Thus, mRNA-based vaccines can circumvent this problem by providing only the mRNA that encodes for antigens, and relying on the cells of the hosts to create the genetic material. The vaccine is able to avoid the risk of infection. Certain mRNA-based vaccines can cause hemorrhaging that could lead to death, but this is extremely rare.

Information about the study

The researchers of the study currently published in the American Journal of Obstetrics & Gynecology MFM identified and recruited eligible women who had been previously vaccinated against COVID-19 and collected umbilical cord blood upon delivery, which was then analyzed for anti-nucleocapsid (N) and anti-spike(S) IgG.

The pathogenesis of the disease is dependent on the severe acute respiratory syndrome coronavirus 2 spike protein. Within the S protein, the receptor-binding domain (RBD) of the S1 subunit binds to the angiotensin-converting enzyme 2 (ACE2) receptor to allow viral cell entry, while the N-terminal domain of the S2 subunit is responsible for membrane fusion. Because of this, the S protein is the focus of the majority of vaccines.

Thus, if the assays provide strong evidence of anti-S IgGs, but no evidence of anti-N IgGs, it is likely that vaccination-induced immunity is the most likely cause of transplacental antibody transmission. A mix of the two would indicate that the mother had been previously infected by COVID-19 or prior monoclonal antibody treatment. The scientists used commercially available immunoassays for detecting anti-N and anti-S IgGs.

Study results

From 36 deliveries, 36 samples were taken. All 36 newborns were positive for anti-S IgGs, with solid results. 31 of these samples also positive for anti-N IgGs.

Generally, the mothers had received their doses between 6 and 25 weeks before the birth and only one woman waiting for her last dose. None of the women in this study had ever been exposed to COVID-19. This is confirmed by the lack of anti-N IgGs. This is a strong proof of the responsibility of the vaccine in the transmission of antibodies.

Studies that have been done to determine the transmission of antibodies between mothers and infants using natural immunity also revealed the presence of anti-N IgGs. This further strengthens the evidence.

The importance of the study in shaping public health policies is highlighted by the authors. Particularly, the authors of the present study stress the need to advise pregnant women to get the COVID-19 vaccine during their pregnancy in order to protect the health of the mother and the fetus and for the protection of the newborn once arrived.

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Gemma Wilson

Gemma is a journalism graduate with keen interest in covering business news – specifically startups. She has as a keen eye for technologies and has predicted quite a few successful startups over the last couple of years.

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