A recent study published in The Journal of Nutrition investigated whether the COVID-19 vaccination or SARS-CoV-2 infection induces compositional changes in human milk. The study found that while SARS-CoV-2 infection led to significant changes in milk composition, including alterations in proteins, metabolites, and lipids, COVID-19 vaccination caused minimal changes, with no detectable vaccine components in breast milk. This study provides reassurance for breastfeeding mothers, highlighting that vaccination does not pose a risk to infant health.
Background
Human milk is the gold standard for infant nutrition, providing essential nutrients, immune cells, and immunomodulatory components that help protect infants. During the COVID-19 pandemic, concerns arose regarding whether the virus or the vaccine could affect the composition of milk. While earlier evidence showed that SARS-CoV-2 does not transmit through breast milk, there was limited data on the potential impacts of vaccination on milk composition.
This study aimed to assess changes in milk composition following COVID-19 vaccination and infection, using advanced techniques to analyze proteins, metabolites, and lipids.
About the Study
The study included lactating individuals aged 18 years or older who either tested positive for SARS-CoV-2 or received a COVID-19 vaccine (Pfizer, Moderna, or Johnson & Johnson). Participants provided milk samples before and after vaccination or infection. These samples were analyzed using multi-omics approaches, including proteomics, lipidomics, and metabolomics.
The analysis utilized sophisticated methods such as mass spectrometry to examine the molecular composition of the milk. Data were analyzed using statistical techniques to detect significant changes in milk proteins, metabolites, and lipids.
Study Results
Changes Following SARS-CoV-2 Infection
SARS-CoV-2 infection caused significant changes in 67 milk proteins, with 43 proteins showing increased expression and 24 showing decreased expression. These changes were primarily related to systemic inflammatory pathways, such as NOD-like receptor signaling and JAK-STAT signaling. Additionally, lipidomic analysis revealed significant alterations in lipid composition, with 385 lipid species exhibiting changes. Pro-inflammatory lipids, such as ceramides, were elevated, while anti-inflammatory lipids were reduced.
Metabolomic analysis also identified 13 altered metabolites, including ascorbic acid and acetaminophen, which were elevated in milk from infected individuals, reflecting maternal responses to the illness.
Minimal Changes After COVID-19 Vaccination
In contrast to SARS-CoV-2 infection, COVID-19 vaccination led to minimal changes in milk composition. No significant alterations were found in the lipid or metabolite profiles of the milk, regardless of the vaccine type. However, proteomic analysis revealed some changes in milk proteins, particularly after Moderna and Johnson & Johnson vaccinations. These changes were transient and vaccine-specific.
The Moderna vaccine led to changes in eight proteins within 1-6 hours post-vaccination, while Johnson & Johnson showed a more pronounced effect with 13 protein changes by day three. Despite these protein changes, the overall impact of vaccination on milk composition was minimal, with no evidence of synthetic vaccine components, such as lipids, mRNA, or adenoviral proteins, in the milk.
No Vaccine Components in Milk
Despite using advanced mass spectrometry, the study found no detectable vaccine components in any of the milk samples. This provides robust evidence that COVID-19 vaccines do not enter human milk, further supporting the safety of breastfeeding following vaccination.
Conclusions
This study highlights that while SARS-CoV-2 infection leads to significant changes in the composition of human milk, COVID-19 vaccination results in minimal, transient alterations with no detectable vaccine components in the milk. These findings emphasize the safety of breastfeeding after vaccination, reassuring mothers that the vaccine does not pose a risk to their infants.
The study underscores the importance of vaccination for protecting lactating individuals and their infants, especially during pandemics. Further research is needed to fully understand the long-term effects of vaccination on milk composition, but current evidence supports the safety of breastfeeding after COVID-19 vaccination.
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