Newborns receive passive immunity through antibody transfer via the placenta and breast milk following natural infection and immunization. Passive immunity is critical for the protection against neonatal infectious diseases as newborns possess an immature immune system, which makes them vulnerable to the ...
Newborns receive passive immunity through antibody transfer via the placenta and breast milk following natural infection and immunization. Passive immunity is critical for the protection against neonatal infectious diseases as newborns possess an immature immune system, which makes them vulnerable to the invasion of pathogenic microorganisms. Recent studies reported that the COVID-19 vaccine in pregnant and lactating women increased SARS-CoV-2-antibodies and transported to infant cord blood and breast milk. Natural infection and vaccination in women can induce antibody responses and T-cell responses against SARS-CoV-2. However, the effectiveness and differences of neutralizing antibodies between natural infection (mucosal immunity) and immunization (systemic immunity) are not well understood. Whether antibody responses in breast milk correlate with protection against neonatal COVID-19 infection remains to be determined. In addition, the durability of SARS-CoV-2-specific antibodies in breast milk in COVID-19-vaccinated women is still unknown.New variants are evolving in SARS-CoV-2, and RBD mutations are associated with enhanced infectivity, greater transmissibility, and a higher capacity to evade/escape from neutralizing antibodies. COVID-19 vaccine or natural infection can educate the immunity, but it still unknown whether antibodies transferred to neonates will protect against the SARS-CoV-2 mutations from variants of concern. Lastly, investigations are required to identify the maternal factors (including genetics, nutrition, preexisting immunity, and health conditions) that enhance the immune responses against pediatric infectious diseases.This Research Topic will focus on Breast Milk and Passive Immunity during the COVID-19 Pandemic. Authors can submit original research, review, mini review, commentary, and opinion articles focused on but not limited to:(1) COVID-19 vaccine and immune responses in breast milk; (2) natural infection and vaccination of COVID-19 in mother-infant immunity; (3) neutralizing antibodies against SARS-CoV-2 from variants of concern in breast milk; and (4) maternal factors improving passive immunity during COVID-19. VDM is an employee at Medolac Laboratories. LB and HVG have no conflict of interest to disclose.
Passive Immunity During PregnancyThe first way for a baby to acquire immunity is called passive immunity, and it occurs during pregnancy. Over a mother’s lifetime, she is exposed to many different pathogens, and her immune system develops the ability to produce a large catalog of antibodies that can act against them. During pregnancy, these antibodies are transported across the placenta to the fetus’s blood supply. These types of antibodies are called immunoglobulin G, or IgG. They are the only antibody type that passes through the placenta to the growing fetus. They are called passive maternal IgGs, because of how they are transferred to the baby. IgGs are the most common type of antibody in our bodies. They help protect us, as well as our unborn babies, from viral and bacterial illnesses. Human babies are born with all of the passive maternal IgG antibodies their mother has during pregnancy. To provide additional, critical passive IgG antibodies that will pass from the placenta directly to the baby’s bloodstream, mothers should strongly consider following the vaccination recommendations during pregnancy. This will help protect the baby from infections such as pertussis (whooping cough), influenza, and other illnesses ahead of their scheduled childhood vaccinations and before their immature and vulnerable immune system begins to produce its own antibodies. Maternal IgG antibodies are temporary though, and they gradually disappear within four to six months after birth. Fortunately, immediately after birth, the baby begins to make their own IgG antibodies in response to viruses and bacteria in their environment and through childhood vaccinations. The immune system is constantly maturing, but children under two are most vulnerable. By five years of age, children have been exposed to many viruses and bacteria and have also received many important vaccinations; therefore they are less vulnerable to serious infections. Premature babies are particularly vulnerable, as they don’t receive the 40 weeks gestation time to receive the full maternal passive immunity that a term baby does. (Most antibodies are transferred in the last four to six weeks of pregnancy.) Maternal IgG antibodies passed through the placenta are very effective in protecting neonates and infants against most infectious diseases. This is why term human babies can be fed properly prepared formula and thrive without the passive immunity that breast milk provides. Evidence has shown, however, that human breast milk, whether through direct breastfeeding, expressed breast milk or human donor milk is critical to preterm babies as it reduces the risk of developing sepsis and a deadly infection called necrotizing enterocolitis (NEC), which affects a baby’s intestines. Passive Immunity Through BreastfeedingThe other way a baby can acquire passive immunity is through breast milk. Colostrum is the first milk a woman produces when she begins to breastfeed, and it contains a large number of antibodies called secretory immunoglobulins (You’ll see this abbreviated as sIgA.) Over 90% of the antibodies are sIgA. IgM and IgG antibodies are also present in tiny amounts. These sIgA antibodies in human milk line the mucous membranes in the baby’s mouth, upper airway, throat, ears, and intestines; here they guard against germs entering the mucosal lining, which is the first port of germ entry, by neutralizing the pathogen. Secretory IgA antibodies can survive being broken down by gastric acid and digestive enzymes in the stomach and intestines. Human babies are not able to absorb these passive maternal antibodies from colostrum or breast milk directly into their bloodstream. Instead, the sIgA antibodies protect against infections by working inside the baby’s gastrointestinal tract and respiratory system. This passive breastfeeding sIgA immunity is dose-dependent, meaning the more breastmilk your baby receives, the more protection they have. The dose-dependent protection continues until the baby is weaned. This passive immunity is invaluable for premature newborns and newborns born in impoverished countries where there is limited access to clean water for safe formula preparation, often leading to severe diarrhea and death. Breast milk immunity offers protection from respiratory and gastrointestinal illnesses; this does not mean prevention. However, breastfed babies can still get sick, because young children get lots of colds, some as many as eight to ten each year, before they turn two years old. For mothers who don’t plan on breastfeeding exclusively for the first 6 months, breastfeeding during the first months is still beneficial, because this is when the baby’s immune system is the most vulnerable. Human milk also contains infection-fighting components that are not antibodies. (*see the full description below ) The second way a baby develops immunity is by ACTIVE OR ACQUIRED IMMUNITY (germ exposure and vaccination)A baby’s immune system is at its most vulnerable right after birth. Since passive immunity from both IgG and IgA forms of maternal immunity is temporary, and breast milk antibodies can only protect the respiratory and GI tracts while breastfeeding is occurring, these measures are not enough to fully protect a baby from infectious diseases. At six months, a baby’s IgG antibodies that were acquired passively from their mother are gone. Their immune systems have started to produce their own IgG antibodies from the germs they are encountering in their world and through vaccinations. This is known as active or acquired immunity, the type of immunity that the body develops after germ or vaccination exposure. To continue the process of protection, babies need to acquire vaccine-induced immunity, and fortunately, vaccination is a safe and effective way to achieve it by boosting immature immune systems without getting the disease. Active immunity is long-lasting and sometimes lifelong.
Vaccines are tested again and again to be sure they are safe for children and nursing mothers. If you are concerned about whether or not a particular vaccine is safe to receive while breastfeeding, check the CDC’s list of vaccines that are safe for nursing mothers and babies. Because breastfeeding provides passive antibodies to a baby, breastfeeding is not a substitute for immunization. During the first months prior to receiving vaccinations, babies are counting on their parents, family, friends, caregivers, doctors, nurses, lactation consultants, and anyone else around them, to protect them from diseases they may not be able to fight off. Everyone being up to date with their recommended vaccines is the best way for a community to support a newborn’s health. A common question I receive is: “Can I breastfeed while I am sick with the flu?”The answer is yes, even if you are taking Tamiflu. The flu is not transmitted through breast milk. Breastfeeding can continue while taking precautions to avoid spreading the flu to the baby. The CDC has excellent guidelines about breastfeeding while having the flu. If a mother is sick from an illness, how long does it take for the antibody to be produced in her breast milk?To be fully informed and to take proper precautions, a mother should know there is a delay between the first exposure to the pathogen and the acquisition of immunity. This process, called the primary response, can take up to fourteen days for optimal antibody production. If a person is exposed to the same pathogen again later, the response is much faster and stronger; this is called a secondary response. To provide additional protection for your baby, hand-washing is an excellent way to help prevent the spreading of germs. According to the CDC, “Regular hand-washing, particularly before and after certain activities, is one of the best ways to remove germs, avoid getting sick, and prevent the spread of germs to others.” It’s quick, it’s simple, and it can keep us all from getting sick. Hand-washing is a win for everyone—except the germs. Another social media post that went viral is Another social media post that went viral isa picture of the color changes of pumped breastmilk from a mother who said her baby was sick. Can this be true? What about the back-wash idea in which a baby’s saliva is sucked into valves within the nipple and the mother’s body produces an immune response that is secreted in her breastmilk. The idea that a baby’s saliva can trigger changes in breast milk was popularized in 2015, and several mothers have posted viral images and claims similar to the above, but even scientists who study breastmilk say the idea that baby saliva changes breast milk is still a hypothesis that needs to be proven or disproven with high-quality research. *Please Note: Human milk also contains the following protective components:
Jody is a champion for debunking pseudoscience in the breastfeeding community because parents need to be truly informed when making parenting decisions. She is also a staunch advocate for protecting underfed breastfed babies and is the reason why she co-founded the Fed Is Best Foundation. She provides parents with the most up to date scientific resources and includes her extensive neonatal nursing knowledge and infant feeding clinical experiences, to help parents make the best infant feeding decision that works for them. Additional references: Immunity Types An Introduction to Active Immunity and Passive Immunity Natural Passive Immunity Human milk: Defense against infection. Infant gut immunity: a preliminary study of IgA associations with breastfeeding. Chapter 50 Immune Defenses Mucosal immunity: integration between mother and the breastfed infant Breastfeeding after maternal immunization during pregnancy: Providing immunological protection to the newborn: A review Breast Milk as the Gold Standard for Protective Nutrients Cells of human breast milk Evolution of the immune system in humans from infancy to old age How do vaccines work?
Influenza (Flu) Changes in immunomodulatory constituents of human milk in response to active infection in the nursing infant Future Research in the Immune System of Human Milk Breastfeeding and infant illness: a dose-response relationship? Kinetics of the antibody response to tetanus-diphtheria-acellular pertussis vaccine in women of childbearing age and postpartum women Additional blogs:
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