Efficient maternal to neonatal transfer of antibodies against SARS-CoV-2 and BNT162b2 mRNA COVID-19 vaccine

Abstract

Background: The significant risks posed to mothers and fetuses by COVID-19 in pregnancy have sparked a worldwide debate surrounding the pros and cons of antenatal SARS-CoV-2 inoculation, as we lack sufficient evidence regarding vaccine effectiveness in pregnant women and their offspring. We aimed to provide substantial evidence for the effect of BNT162b2 mRNA vaccine versus native infection on maternal humoral, as well as transplacentally acquired fetal immune response, potentially providing newborn protection.Methods: A multicenter study where parturients presenting for delivery were recruited at 8 medical centers across Israel and assigned to three study groups: vaccinated (n=86); PCR-confirmed SARS-CoV-2 infected during pregnancy (n=65), and unvaccinated non-infected controls (n=62).Maternal and fetal blood samples were collected from parturients prior to delivery and from the umbilical cord following delivery, respectively. Sera IgG and IgM titers were measured using Milliplex MAP SARS-CoV-2 Antigen Panel (for S1, S2, RBD and N).Results: BNT162b2 mRNA vaccine elicits strong maternal humoral IgG response (Anti-S and RBD) that crosses the placenta barrier and approaches maternal titers in the fetus within 15 days following the first dose. Maternal to neonatal anti-COVID-19 antibodies ratio did not differ when comparing sensitization (vaccine vs. infection). IgG transfer ratio at birth was significantly lower for third-trimester as compared to second-trimester infection. Lastly, fetal IgM response was detected in 5 neonates, all in the infected group. Conclusions: Antenatal BNT162b2 mRNA vaccination induces a robust maternal humoral response that effectively transfers to the fetus, supporting the role of vaccination during pregnancy.

Covid-19 Vaccination in Pregnancy: A Systematic Review

“…12 Antibody transfer was also reported. 12,14,15,17,18,20,21 Cord blood antibody and maternal antibody levels were about equal. 18 Additionally, latency and number of doses were correlated with the antibody transfer strength.…”

“…Moreover, administration of the second dose can further increase the IgG level among vaccinated women. 11,20 Spike-and RBD-IgG titer rose rapidly after prime dose (p<0.0001 and p<0.01, respectively); and after receiving booster, it became higher than that of the prime dose (p<0.05 and p<0.001, respectively). 11 Vaccination elicited IgG responses against S1, S2, and RBD but not N protein.…”

“…An earlier Covid-19 infection may provide a better placental antibody transfer. 20 Additionally, poor placental antibody transfer was exclusively observed only in the third trimester of pregnancy, even though the maternal antibody response was significantly higher. 47 Natural infection may result in higher morbidity and mortality 48 , so vaccination should be the better option for the dyads.…”

“…Yet, S2 IgG and N IgG were higher in infected pregnant women (p=0.016 and p<0.0001, respectively). 20 Meanwhile, reported that Spike IgG titer is higher in vaccination than that of natural infection in pregnant women. 11 Maternal SARS-CoV-2 spike protein IgG levels between vaccinated and uninfected unvaccinated pregnant women are 22.8±14.5 AU and 0.04±0.05 AU, respectively (p<0.001).…”

Safety and efficacy of COVID-19 vaccines in pregnant women with rheumatic diseases: an immunologic perspective

“…Recent studies show promising effects of antibody development in pregnant women after mRNA vaccination which crosses the placenta and protects the fetus. Also, placental examination of vaccinated women was no different than those of non-vaccinated reducing concerns of antibody-induced placental damage [ 16 , 17 , 18 ]. This opens the doors to confirm immunogenicity in pregnant women with RDs.…”