Pregnant women vaccinated against COVID-19 could pass along protection to their babies in the womb, according to a new study in Israel.

According to the research conducted in February, antibodies were detected in all 20 women administered both doses of the Pfizer/BioNTech vaccine during their third trimester of pregnancy and in their newborns, through placental transfer.

“Our findings highlight that vaccination of pregnant women may provide maternal and neonatal protection from SARS-CoV-2 infection,” the study said.

The findings by researchers from Jerusalem’s Hadassah- University Medical Centre were posted this month on medRxiv an online distribution service for unpublished research manuscripts that have not been peer-reviewed – and reported by Israeli media.

The authors noted the small size of the study and said further research was necessary to gauge the effect of vaccination at different stages of pregnancy, and the safety and efficacy of the different vaccines now available.

One of the researchers, Dana Wolf, was quoted by the Jerusalem Post as saying the group would now start looking at how long the antibodies triggered by the vaccinations would last in the babies.

Pfizer Inc and BioNTech SE said last month they had started a 4,000-volunteer international study to evaluate the safety and effectiveness of their COVID-19 vaccine in healthy pregnant women.

The trial would also assess whether vaccinated pregnant women transfer protective antibodies to their babies.

A separate U.S. study posted last week and also awaiting peer review, found that the antibodies induced in pregnant women from mRNA COVID-19 vaccines, such as the Pfizer/BioNTech and Moderna Inc shots, were transferred to the babies via the placenta or breast milk.