Babies get Covid-19 immunity from mothers while in the womb: Study

Women who get infected with Covid-19 while pregnant are not likely to pass it on to their babies.

The babies receive some form of natural immunity from their mother’s antibodies when they are still in the womb, shows a new study published in the JAMA Paediatrics journal.

The researchers say that even when there is a slight chance of transfer of the virus, most women who had been infected in the study provided protection mechanisms instead of viral transmission.

The worry was whether the babies could get infected after delivery from other members of their household.

“We did not detect IgM (Immunoglobulin M fights new infection) antibodies in any cord blood serum samples (blood from the umbilical cord of a newborn) even in cases of critical maternal illness or preterm delivery, supporting that maternal-foetal Sars-Cov-2 transmission is rare,” said the researchers.

The study instead identified IgG antibodies (Immunoglobulin G protects against bacterial and viral infections like the coronavirus) in 72 blood samples from the babies out of the 83 mothers who had been infected with Covid-19 and were part of the study.

Severe symptoms

A higher percentage of the women who were found to be positive and transferred the antibodies to their children were asymptomatic. Therefore, the researchers could not track when they were infected with the virus.

“Higher maternal antibody concentrations and a higher transfer ratio were associated with increasing duration between onset of maternal infection and time of delivery,” the study said.

As a result, the researchers recommended vaccination of women since the Centers for Disease Control and Prevention lists pregnancy as one of the risky conditions should one get infected with Covid-19.

“When vaccines are widely available, the optimal timing of maternal vaccination during pregnancy will need to consider maternal and foetal factors, including the time needed to ensure neonatal protection,” said the researchers.

A study published in September 2019 in the BMJ said pregnant women were not likely to get severe symptoms of Covid-19. But, should they get critically ill, the severity of the disease could escalate to the point of need for critical care.

The study also revealed the Covid-19 positive women were likely to get their babies before their due date and the babies will also be admitted in the neonatal unit. The findings of these two studies show the need to vaccinate pregnant women who are susceptible to Covid-19.

On Friday, the World Health Organization changed tune regarding their interim guidance on vaccinating Covid-19 positive pregnant women using the Moderna vaccine (mRNA-1273).

Infant infection

“WHO recommends not to use mRNA-1273 in pregnancy, unless the benefit of vaccinating a pregnant woman outweighs the potential vaccine risks, such as in health workers at high risk of exposure and pregnant women with comorbidities placing them in a high-risk group for severe Covid-19,” warned WHO.

The new twist now upholds the use of vaccines on pregnant women and is in sync with other regulatory bodies like the CDC.

“Based on what we know about this kind of vaccine, we do not have any specific reason to believe there will be specific risks that would outweigh the benefits of vaccination for pregnant women,” read the WHO advisory.

The researchers, however, said there was more room for study in maternal versus infant infection in relation to Covid-19.

“Further studies are needed to determine if Sars-Cov-2 antibodies are protective against newborn infection. If so, at what concentration; and whether the transplacental (passing through the mother to foetus via a placenta) kinetics of vaccine-elicited antibodies are similar to naturally acquired antibodies,” advised the researchers.