How Vaccination During  Pregnancy Pass on Antibodies to Newborns

How Vaccination During Pregnancy Pass on Antibodies to Newborns

01.Oct.2021

In the Journal of Immunology, a group of scientists from the University of Zaragoza in Spain recently published their findings on maternal antibody transfer to newborns after vaccination during pregnancy. This study paves the way for further research investigating if mothers can give passive immunity to infants before they are able to receive vaccinations themselves. Passive immunity is an immediate protection against disease, where the body has to do little to nothing for this protection. This is because antibodies are transferred from one individual (the mother) into another (the child).


Passive immunity can last anywhere from a few days or weeks up to months or years, depending on how long it takes for the passively acquired antibodies to break down. This is why mothers who are breastfeeding tend to give their infants passive immunity to protect them while they are too young to receive vaccines.


Maternal vaccination during pregnancy can be considered a form of partial passive immunity. For this reason, many scientists have hypothesized the possibility of vaccinating pregnant women in order for them to pass on these antibodies before their children are old enough to receive vaccinations themselves. There is evidence that this approach would be safe and effective, but only limited studies have been done thus far.


As Dr. Juan José Güerri, the lead author of the study explains, “The protective mechanisms against infections during pregnancy are not well known”. Previous research showed that the levels of antibodies in newborns increased if their mothers were given vaccines during pregnancy, but it was unclear as to how this might have occurred.


In order to find an answer, Dr. Andrés Moreno and his colleagues from the University of Zaragoza performed a study with mice. After immunizing pregnant mice with an FDA-approved vaccine, they observed that some of the antibodies were transferred to newborns. The researchers found out how this occurred by performing an experiment where newborn mice had their thymus (a gland involved in the development of immune cells) removed; when this happens, these mice are unable to produce T cells (another form of white blood cell) and also unable to produce antibodies.


As Güerri explains, “This work demonstrates how immunization during pregnancy results in the transfer of specific maternal IgG antibodies to the offspring by crossing the placenta and accumulating in different tissues”. This is an important finding because it helps us understand how this process works and that there is a potential for the use of vaccines to be given during pregnancy.


In addition, this research also paves the way for future studies about whether a similar effect can occur with other vaccines and, if so, what mechanisms might transfer the antibodies from the mother’s bloodstream into her placenta and then to her unborn child. Dr. Güerri concluded, “The concept of active and passive protection during early life is very interesting. Our results suggest that maternal vaccination may be an effective way to provide immediate protection against infections to newborns”.


This study was funded by the Spanish Ministry of Economy and Competitiveness (MINECO), FEDER funds, European Regional Development Funds, and the Kutxa Foundation. Dr. Andrés Moreno is a member of the Research Group in Immunopathology and Neuroimmunology of Infectious Diseases at the University of Zaragoza.