A new study by researchers from Hadassah-University Medical Center showed that pregnant women who get vaccinated against coronavirus could pass along their immunity to their babies.
The study, which has thus far only been published on MedRxiv and therefore not peer reviewed, evaluated the level of Immunoglobulin G (IgG) antibodies of 20 pregnant women who had received two shots of the Pfizer coronavirus vaccine during their third trimester, and their infants. In all cases, these antibodies were detected at adequate levels both in the mothers’ blood and in cord blood.
“Neonatal protection from infection is primarily dependent on maternally derived antibodies that are transferred via the placenta,” Dana Wolf, director of the Clinical Virology Unit at Hadassah who is one of the lead researchers on the study, told The Jerusalem Post. “We demonstrated an efficient placental transfer of IgG antibodies – the kind of antibodies that are triggered by infection or following vaccination.”
The researchers specifically measured the level of antibodies against the SARS-CoV-2 spike protein and its receptor binding domain, which would show whether the antibodies would protect against COVID-19. Wolf said the level and type of antibodies were suggestive of “being able to sufficiently block the virus.”
The study was conducted in February, very soon after the first pregnant women began being vaccinated in Israel. Wolf said the study is ongoing and the team is now evaluating the level of antibodies in women who were vaccinated earlier in their pregnancies, too.
Wolf, who worked on the study with a handful of other experts – including top obstetricians Dr. Amihai Rottenstreich and Shay Porat – said that the group will now start looking at how long the antibodies will last in the babies.
Placental transfer of antibodies is not uncommon. For example, pregnant women are commonly vaccinated against pertussis in order to protect their newborns from developing the illness.
Since the start of the third wave, dozens of pregnant women have ended up in intensive care units after contracting COVID-19. In most cases, they were forced to deliver their babies early via emergency C-sections. In the worst cases, some of the women died.
Wolf said that, “the vaccine protects the women from severe disease and now we believe it also could help protect their babies during the early period of life.”