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Breastfeeding after receiving COVID-19 booster shot gives babies immunity

Lactating mothers who receive the COVID-19 booster shot can pass protective antibodies to their infants through breastfeeding. This pioneering research from the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) and the UF College of Medicine underscores the potential for breastfed babies, who are too young for vaccination, to gain a layer of protection against the virus.

This investigation marks the third in a series aimed at understanding the transfer of COVID-19 antibodies via breast milk. Initially focusing on the antibodies generated after the primary vaccination series, the research has now advanced to explore the impact of the booster shot.

The findings, published in Frontiers in Nutrition, were supported by funding from the Gerber Foundation and the Children’s Miracle Network.

Protective power of breastfeeding against COVID-19

Dr. Vivian Valcarce, a pivotal figure in this study and now an assistant professor at the University of Alabama at Birmingham, emphasized the critical nature of breast milk in safeguarding infants, particularly in their first six months.

“We think that breast milk may play an important role in protecting the infants during the first six months of life from COVID. We continue to see babies being hospitalized from COVID-19 infections,” Valcarce said.

Despite ongoing vaccination efforts, infants continue to face hospitalization risks due to COVID-19, making the role of breast milk even more vital. The study delved into how the introduction of the COVID-19 booster shot affects the presence and efficacy of antibodies in breast milk.

Joseph Larkin, a UF/IFAS associate professor of microbiology and cell science, highlighted the dual importance of the research.

First, it demonstrates that breastfeeding offers a way to provide infants with COVID-19 antibodies. Next, it shows that these antibodies, which naturally wane over time, are replenished following a booster shot, extending the protective benefits for breastfed babies.

“When babies are born, they have an immature immune system, so they rely heavily on mom’s immune system,” Larkin explained. “Breastfeeding can serve as a gap in between while babies are building their own immune system.”

Tracing the path of antibodies

Researchers engaged in a comprehensive analysis, tracking 14 lactating mothers and their infants from pre- to post-booster shots.

This included testing the mothers’ blood and breast milk for antibodies and analyzing infants’ stool samples to confirm the transmission of these protective agents.

A novel aspect of the study involved testing the functionality of breast milk antibodies against a laboratory-safe strain of COVID-19, revealing that these maternal antibodies are capable of neutralizing the virus.

Lauren Stafford, a UF/IFAS graduate research assistant, and Ph.D. candidate, along with Dr. Josef Neu, a professor of pediatrics within the division of neonatology at the UF College of Medicine, contributed significantly to the study.

The future of breastfeeding and COVID-19

The magnificent work of these scientists underscores the invaluable role of breastfeeding in bolstering infant health, particularly during a pandemic.

Their findings highlight the importance of breastfeeding as a protective strategy against COVID-19 for infants and reinforces the critical role of booster vaccinations for lactating mothers.

By providing an additional layer of defense through breast milk, mothers can play a pivotal role in safeguarding their infants’ health during these challenging times.

The full study was published in the journal Frontiers in Nutrition.


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