Antibodies produced by the pregnant woman after being vaccinated pass to the fetus through the placenta; after birth, the booster continues with breastfeeding
Immunization is an essential care that should be part of every pregnant woman’s prenatal care. In addition to avoiding serious health problems at a time when the body is most vulnerable, women who keep their vaccination records up to date protect their babies from serious diseases, since they pass their own antibodies to the fetus via the placenta in a process known as “immunization”.passive immunization”. After birth, breastfeeding continues to help strengthen the child’s immunity.
“Newborns have an immature immune system that is still developing and learning how to respond appropriately to the ‘aggressions’ present in the environment outside the uterus. Therefore, they are more susceptible to infections caused by viruses and bacteria.“, says Ivo Lebrun, a scientific researcher at the Butantan Biochemistry Laboratory. Even though children receive several doses of vaccine early in life, it is only at 6 months of age that their immunity begins to gain strength.
According to the vaccination schedule recommended by the Ministry of Health, pregnant women should receive a booster of the dTpa vaccine – known as triple bacterial – in order to protect babies against neonatal tetanus, diphtheria and whooping cough. If they are not up to date with their doses, they need to update their immunization schedule against hepatitis B and dT, in addition to receiving seasonal immunizations from the flu and COVID-19 campaigns.
“Women who intend to become pregnant soon can include a complete assessment of their vaccination records in their planning. This will give them the opportunity to update or complete the schedule of immunizations that are not recommended during pregnancy, such as MMR and yellow fever.”, advises the medical consultant at CeVivas (Center for Viral Surveillance and Serological Evaluation) and operations facilitator at the Butantan Scientific Development Center, Antônio Jorge Martins.
TRANSFER OF ANTIBODIES THROUGH THE PLACENTA
When a pregnant woman receives a vaccine, her immune system kicks into action to fight the “invading agent” – even if the virus or bacteria expressed in the vaccine is not capable of triggering an infectious condition.
First, there is the production of IgM antibodies, which have a nonspecific action and promote a first attack on the microorganism. About a week later, the IgM levels decrease and IgG (immunoglobulins G) come into action, which carry a “specific” capable of neutralizing the antigen. This is the antibody that the mother will pass to her child through the placenta.
The embryonic annex developed during gestation is the meeting point of the maternal and fetal circulatory systems – this metabolic exchange allows the development of functions that the fetus is not yet capable of performing independently within the uterus.
As in a type of “transfusion”, the placenta carries oxygen, nutrients and other substances essential for the baby’s development to the baby through the umbilical cord; at the same time, it also eliminates waste, such as carbon monoxide, uric acid and urea, released into the mother’s bloodstream.
Even though they have a high molecular weight, the IgG antibodies present in the pregnant woman’s body are able to cross the placental barrier and reach the fetal circulation. Transport occurs through a process called transcytosis: when a cell captures, moves and secretes a specific molecule. It is estimated that active transport of immunoglobulin G begins from the 13th week and continues throughout the pregnancy. After 6 months of life, the child begins to produce its own IgG.
IMMUNITY THROUGH BREASTFEEDING
One hypothesis is that the IgG antibodies produced by the mother’s vaccination can also be mobilized into breast milk, thus ensuring an immunological boost for the baby even after birth.
“Since there is a large vascularization in the mammary gland region, one possibility is that the antibody is captured from the mother’s bloodstream in a process similar to what happens in the placenta. Thus, when the baby breastfeeds, he or she also receives the antibodies.”, says Ivo Lebrun.
From then on, the alternative is that these molecules passed from mother to child through milk go to the gastrointestinal tract.”Since digestion in the intestine is not so acidic at the beginning of life, the substance would not be degraded, but rather absorbed, entering the baby’s bloodstream.”, says the researcher from the Butantan Biochemistry Laboratory.
During the COVID-19 pandemic, a study conducted by the Hospital das Clínicas of FMUSP (School of Medicine of the University of São Paulo) indicated the presence of antibodies capable of neutralizing Sars-CoV-2 in the milk of lactating employees immunized with CoronaVac. The samples indicated a high concentration of antibodies after the women received the second dose of the vaccine – the levels remained high even after months of breastfeeding.
Breast milk – especially colostrum, a thick, yellowish liquid produced by a woman’s body shortly after giving birth – also has high concentrations of IgA antibodies, a type of immunoglobulin that protects the respiratory and gastrointestinal mucous membranes from the action of microorganisms.
“When ingested, these molecules create a type of barrier that prevents viruses and bacteria from attaching themselves to the tissues in the region and crossing the mucosa. It is as if the tissues were coated with a type of ‘varnish’ that makes the invading agents ‘slip’ until they are eliminated in the feces.”, said Antonio Jorge.
Beyond nutrition: breast milk stimulates the immune system, regulates blood pressure and contributes to the well-being of babies.
It is no wonder that breast milk is considered the first “vaccine” of the baby. Produced “tailor made” through the mother’s body, the food strengthens the immune system, reduces the risk of obesity, diabetes, diarrhea and respiratory infections.
With the aim of reinforcing the importance of exclusive breastfeeding up to 6 months of age, since 1992, the month of August has been marked by the implementation of several actions in favor of the theme. In Brazil, the initiative, supported by the Ministry of Health, was named Golden August in reference to the gold standard of food quality.
With information from Government of the State of Sao Paulo.
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