It seems incredible how little we knew a year ago and how much we are learning every day about the coronavirus. We have been able to know that pregnant women who have had Covid-19 transfer antibodies of the disease to their babies through the placenta, but we did not know how long that protection lasts once the baby is born.
A Spanish multicenter study in which experts from the Gregorio Marañón and Infanta SofÃa hospitals in Madrid, as well as the Reina SofÃa in Tudela (Navarra), have participated, and which has been presented at the 2nd National Covid-19 Congress, indicates that babies born of mothers who had Covid-19 and received antibodies through the placenta, lose them throughout the first six months after delivery.
The researchers observed that the passage of antibodies through the placenta to newborns was very common among mothers with Covid-19. They also point out that cases of neonatal infection were rare ; it only occurred in five children whose mothers were acutely infected at the time of delivery, without having had time to develop antibodies.
How long do antibodies last in the baby?
According to Europa Press, in order to carry out the study, the data of 141 women with SARS-CoV-2 infection during pregnancy or delivery who gave birth between March and November 2020 were analyzed. vaccinated mothers, but those who have passed the disease.
Epidemiological, clinical and microbiological information was collected from the mothers and their children, determining the IgG antibodies against the coronavirus , which are generated once the active infection has been overcome.
The pregnant women were divided into three groups, according to their situation against COVID-19 in childbirth. 34% had an acute infection, 30.5% had a recent infection, and 35.5% had a past infection at the time of delivery.
- In the group of women with acute infection (PCR positive, IgG negative at delivery), no newborn had positive IgG in cord blood. At two months, 42.8 percent of mothers and 11.5 percent of children had positive IgG, while at six months 33.3 percent of mothers and no children had it.
- In the group of women with recent infection (PCR and IgG positive at the time of delivery), 90.9 percent of the newborns had positive IgG in cord blood. At two months, 95.8 percent of the mothers and 57.1 percent of the children were IgG positive, and at six months, 83.3 percent of the mothers and no children.
- In the group with past infection (negative PCR, with documented infection during pregnancy), 80 percent of mothers and 84.4 percent of newborns were IgG positive at delivery. At two months, 82.3 percent of mothers and 64.7 percent of children; and at six months, 57.1 percent of mothers and 14.3 percent of children.
What does the data tell us?
We interpret that the majority of newborns of mothers who have passed the infection in pregnancy or at the time of delivery have antibodies at birth (84.4 and 90.9 percent, respectively).
But as time passes, the antibodies decrease . At two months, they remain in just over half of babies, being somewhat higher in babies whose mothers have passed the infection during pregnancy (64.7 percent), decreasing as the infection has been suffered closer. of childbirth. This is because it has not had time to develop that immunity through antibodies.
On the other hand, we can observe that only in the case of past infection during pregnancy, antibodies remain in the baby six months after delivery, but the percentage is low: less than 15 percent of children. In the other cases, at six months all the children had lost their immunity, indicating that the protection transferred by the mother is lost in the first six months of life .
Regarding mothers, the highest percentage of mothers with antibodies (almost all, 95.8 percent) occurred two months after having suffered the disease with a positive PCR at the time of giving birth. This protection is also decreasing, but is still considerable at six months after delivery.
It would be necessary to see in later studies if the same happens in the case of mothers who have received the vaccine, and from this, to assess when it would be convenient to vaccinate the babies to protect them against infection.
And another thing that should be assessed, which has not been included in this study, is how long the antibodies that the mother transfers to the baby through breast milk protect.
In Babies and more | Pfizer and Moderna vaccines against Covid are effective in pregnant women and protect the baby, concludes the largest study so far
