Role of maternal COVID‐19 vaccination in providing immunological protection to the newborn

Abstract

Pregnant and postpartum individuals are known to have an elevated risk of severe COVID‐19 compared with their non‐pregnant counterparts. Vaccination is the most important intervention to protect these populations from COVID‐19‐related morbidity and mortality. An added benefit of maternal COVID‐19 vaccination is transfer of maternal immunity to newborns and infants, for whom a vaccine is not (yet) approved. Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2)‐specific binding and neutralizing antibodies are present in infant cord blood and breast milk following natural maternal infection and transfer of maternal immunity following COVID‐19 vaccination is an area of active research. In this review, we synthesize the available research, discuss knowledge gaps, and outline factors that should be evaluated and reported when studying the transfer of maternal immunity following COVID‐19 vaccination. The data reviewed herein suggest that maternal SARS‐CoV‐2‐specific binding antibodies are efficiently transferred via the placenta and breast milk following maternal mRNA COVID‐19 vaccination. Moreover, antibodies retain strong neutralizing capacity. Antibody concentrations appear to be at least as high in infant cord blood as in the maternal serum, but lower in breast milk. Breast milk IgA rises rapidly following maternal vaccination, whereas IgG rises later but may persist longer. At least two COVID‐19 vaccine doses appear to be required to reach maximal antibody concentrations in cord blood and breast milk. There is no indication that infants consuming breast milk from vaccinated mothers experience serious adverse effects, although follow‐up is limited. No clear pattern has emerged regarding changes in milk supply following maternal vaccination. The heterogeneity in important methodological aspects of reviewed studies underscores the need to establish standard best practices related to research on the transfer of maternal COVID‐19 vaccine‐induced immunity.

Safety and protective capability of an inactivated SARS-CoV-2 vaccine on pregnancy, lactation and the growth of offspring in hACE2 mice

“…Thus far, there is no evidence to suggest that a vaccine against SARS-CoV-2 is harmful to either lactating women or breastfed infants. Many international health organizations, including the Center for Disease Control and Prevention in the US, the Society for Maternal-Fetal Medicine, Gynecologists of Canada, and the American College of Obstetricians and Gynecologists, have recommended the administration of vaccines to pregnant and lactating individuals [16] . The WHO also suggested that pregnant women should discuss with their healthcare provider and obtain a vaccine when the benefits of vaccination outweigh the potential risks.…”

Attitudes and Beliefs Associated With COVID-19 Vaccination During Pregnancy

“…For example, local and national health campaigns can provide real-time access of pregnant people and their health care clinicians to the growing scientific evidence demonstrating transplacental and breastmilk antibody transfer following COVID-19 vaccination. 4 , 5 , 6 It is also important to continue research maintaining vaccination in pregnancy registries and publish data on long-term health outcomes of vaccinated pregnant people and their infants. The limitations of this study include low representation of racial groups other than Black and White, and the results may not be representative of other US regions, and a cross-sectional survey design with assessment of attitudes toward COVID-19 vaccination only once during pregnancy.…”

What is the Hidden Biological Mechanism Underlying the Possible SARS-CoV-2 Vertical Transmission? A Mini Review

“…Due to the negative effect of this infection on pregnancy, considerable support to pregnant patients comes from the implementation of the vaccination campaign. The American College of Obstetricians and Gynecologists (ACOG), the Society for Maternal-Fetal Medicine, the Centers for Disease Control and Prevention (CDC), and the Italian Society Of Gynecology and Obstetrics (SIGO) encourage SARS-CoV-2 vaccination in pregnancy ( ACOG, 2018 ; CDC, 2021 ; Sigo Position Paper, 2021 ; European Center for Disease Prevention and Control, 2020 ), which also provides an immunological protection for the newborn ( Jorgensen et al, 2022 ). In fact, pregnant women generate robust humoral immunity after the mRNA anti SARS-CoV2 vaccination ( Gray et al, 2021 ; Shimabukuro et al, 2021 ).…”

“…SARS-CoV-2 specific antibodies are present in both maternal and cord blood, suggesting that antibodies elicited by SARS-CoV-2 immunization cross the placenta ( Beharier et al, 2021 ; Collier et al, 2021 ; Gray et al, 2021 ; Mithal et al, 2021 ). Both spike (S) and receptor binding domain (RBD) IgG antibodies as well as neutralizing antibodies are transplacentally transferred to the newborns, suggesting vaccines as the most important intervention to protect pregnant and breastfeeding women and their offspring from the infection ( Jorgensen et al, 2022 ). To date, one of the most debating issues is to determine the most appropriate timing to assure an effective protection for this dyad.…”