Impact of SARS-CoV-2 Infection and Vaccination on Pregnancy Outcome and Passive Neonatal Immunity

Background: During the SARS-CoV-2 pandemic, many women were infected or received vaccinations against the virus before or during their pregnancy. Little is known about the possible consequences of vaccination or infection on obstetric outcomes, as well as antibody levels against other infectious agents, such as the TORCH pathogens. Methods: A total of 136 pregnant women were included in our study between March 2022 and February 2024. The concentrations of antibodies against nucleocapsid (NCP), the spike protein of SARS-CoV-2, as well as IgG and IgM antibodies against TORCH, were assessed in the maternal and umbilical cord blood. Results: The patients were grouped into the following categories according to responses given in the questionnaire and antibody titer: controls (neither infected nor vaccinated; N = 17), infected only (N = 35), vaccinated only (N = 21), acutely infected (N = 15), and both vaccinated and experienced a COVID-19 infection (N = 47). No differences between the groups in terms of pregnancy outcomes were found. The presence of IgG antibodies against NCP or spike protein in maternal blood was dependent on the patient's vaccination status or previous infection, correlating with that in cord blood. The level of maternal IgG against spike protein correlated negatively with TORCH antibodies. Conclusions: The present study demonstrates the infection- and vaccination-dependent formation of SARS-CoV-2-specific antibodies in the mother and their transfer to the unborn child. Further studies are necessary to investigate the interaction between SARS-CoV-2-specific antibodies and antibodies formed by infection (e.g., CMV) or vaccination against other pathogens in the mother and transmitted transplacentally to the unborn child.