A new study led by researchers from the University of Massachusetts Amherst reveals that women who received COVID-19 mRNA vaccine transfer the SARS-CoV-2 antibodies they developed to their babies by breastfeeding them, leading them to have passive immunity against the virus.
Researchers in the study titled "Neutralizing Antibodies and Cytokines in Breast Milk After Coronavirus Disease 2019 (COVID-19) mRNA Vaccination," published in Obstetrics & Gynecology, measured immune response to the COVID-19 mRNA vaccine in infant stools and breast milk.
Detecting Antibodies in Infant Stools
The recent study is the first research to detect SARS-CoV-2 antibodies in stools from babies of vaccinated mothers.UMAS Ph.D. candidate and study lead author Vignesh Narayanaswamy said that the findings of the study showed that babies could be transferred via breast milk, which provides evidence to convince women to continue breastfeeding after they got vaccinated.
According to the university's press release, about 30 lactating women in the US were enrolled in the study. Most of them were healthcare workers who received the COVID-19 mRNA vaccine between January and April 2021. Participants were asked to provide breast milk samples before they were vaccinated and gave their blood samples. Infant stools were collected 21 days after their mothers were vaccinated.
Researchers tested or the receptor-binding domain (RBD)-specific IgA and IgG antibodies in both breast milk and infant stools samples. They found that both models have neutralized spike protein of SARS-CoV-2 and four of its variants. More so, there was a significant increase in cytokine levels in breast milk samples.
Meanwhile, they detected 33% anti-IgG and 30% anti-IgA antibodies in infant stool samples, which correlate with the vaccine side effects found in the mothers. Researchers noted that vaccinated women who experienced sickness from the vaccine are associated with greater antibodies in the infant stool.
Experts have been encouraging mothers and pregnant women to get vaccinated. Although they were not part of the clinical trials in making the vaccines, researchers said that the findings show that there is a significant benefit that pregnant women and mothers could get from the vaccine that they can pass to their babies.
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Safety and Effectiveness of COVID-19 Vaccines to Pregnant Women
The Centers for Disease Control and Prevention (CDC) said that evidence about the safety and effectiveness of COVID-19 vaccination during pregnancy outweigh any known or potential risks of vaccination while pregnant. Here are a compiled summary of the said growing evidence according to CDC:
- None of the COVID-19 vaccines contain the live SARS-CoV-2 virus that can make anyone sick, including pregnant women.
- Reassuring safety data of mRNA vaccines of Pfizer-BioNTech and Moderna, which showed no increased risk for miscarriage.
- Studies showed that vaccination lowered the risk of infection from SARS-CoV-2 during pregnancy.
- Receiving mRNA vaccines build antibodies in pregnant women similar to people who are not pregnant.
- Animal studies show no significant safety concerns on testing Moderna, Pfizer-BioNTech, and Janssen COVID-19 vaccine before or during pregnancy.
- Vaccines that use viral vectors, such as the Janssen COVID-19 vaccine, have no adverse pregnancy-related outcomes affecting the baby, suggesting that viral vector vaccines work.
CDC also urges pregnant women who received a COVID-19 vaccine to enroll in v-safe, which is a smartphone-based tool that provides personalized health check-ins after vaccination.
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