Authors: Ixtlilxochitl Flores-Fong, Julia Aurora Pérez-Montaño, Jesús Alonso Amézcua-López, Edgar Balcázar López, Josué Raymundo Solís-Pacheco, José Martín Ruvalcaba-Gómez, Blanca Rosa Aguilar-Uscanga.
Background: Breastfeeding provides newborns with the nutrients and biological compounds necessary for their development. The COVID-19 pandemic generated concern in the health sector due to the lack of knowledge of the risk of transmission of SARS-CoV-2 from the mother to her child. It has been shown that human milk does not transmit the virus but rather provides antibodies against SARS-CoV-2.
Objectives: The aim was to evaluate the presence of lactic acid bacteria (LAB), and nutritional and immunoglobulin content in the human milk of mothers sick with COVID-19 and vaccinated to determine the effect of the disease and the vaccine applied on breast milk.
Materials and Methods: During the pandemic (March–April 2021), human milk samples were collected from breastfeeding mothers who had COVID-19 or were vaccinated. The mothers were divided into three groups: (1) healthy, (2) COVID-19 positive, and (3) vaccinated against SARS-CoV-2. Immunoglobulin levels were measured using ELISA assays with specific kits, and macronutrient concentrations (proteins, lipids, and lactose) along with energy content were analyzed using LACTOSCAN SA (Milplan). Additionally, the content of lactic acid bacteria (LAB) was determined by CFU/mL, and PCR was performed to analyze Lactobacillus gene expression.
Results: The results showed that milk from vaccinated mothers had higher fat and lactose content associated with healthy mothers, suggesting that vaccination might affect certain nutritional components of breast milk. Likewise, COVID-19-infected and vaccinated mothers showed higher calorie levels, which could reflect an adaptive metabolic response to the infection. A significant decrease in LAB was also observed in the milk of COVID-19-infected mothers.
Conclusion: COVID-19 infection, like maternal vaccination, can influence human milk's nutritional composition and LAB content. Although these variations in composition do not seem to compromise the nutritional quality of milk, they highlight the importance of continuing to investigate the long-term effects of both infection and vaccination on lactation.
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