Persistence of Anti SARS-CoV-2 Antibodies in Breast Milk from Infected and Vaccinated Women after In Vitro-Simulated Gastrointestinal Digestion

Abstract

Breastfeeding is key for infant development and growth. Breast milk contains different bioactive compounds including antibodies. Recent studies have demonstrated the presence of breast milk SARS-CoV-2 antibodies after maternal infection and vaccination. However, the potential impact on the infant has not been explored yet. As a first step, we aimed at assessing the potential persistence of SARS-CoV-2 IgA and IgG antibodies from infected and vaccinated women in the gastrointestinal tract of the infants by means of an in vitro-simulated gastrointestinal digestion approach. Breast milk samples from 10 lactating women receiving mRNA vaccination against SARS-CoV-2 (n = 5 with BNT162b2 mRNA and n = 5 with mRNA-1273) and also, COVID-19 infected (n = 5) were included. A control group with women with no exposure to the virus (n = 10 pre-pandemic) were also studied. The presence of IgA and IgG SARS-CoV-2 antibody levels was determined by ELISA after the gastric and intestinal stages. The impact of digested antibodies on infant gut microbiota was tested by simulating colonic fermentation with two different fecal inoculums: infants from vaccinated and non-vaccinated mothers. Specific gut microbial groups were tested by targeted qPCR. In vitro infant gastrointestinal digestion significantly decreased the levels of both anti-SARS-CoV-2 IgA and IgG. However, both remained resistant in all the study groups except in that evaluating breast milk samples from infected women, in which IgG was degraded below the cut-off values in the intestinal phase. No effect of the antibodies on microbiota were identified after digestion. In conclusion, antibody levels against SARS-CoV-2 are reduced after in vitro-simulated gastrointestinal tract but remain present, so a positive biological effect could be expected from this infant immunization pathway.

Establishment of a measurement system to evaluate breast milk transfer of biological agents using dry filter paper: A multi‐institutional study

“…32 Similarly, a study of breast milk samples from nursing mothers who received mRNA vaccination against SARS-CoV-2 reported that gastrointestinal digestion of infants significantly decreased the levels of anti-SARS-CoV-2 IgA and IgG. 33 Additionally, a study examining the breakdown of antiphlogistic syncytial virus sIgA/IgA and IgG in human milk from four donors reported a reduction to 33% in the intestinal stage of simulated digestion. 34 The effect on the systemic immune system of breastfed infants is thought to be negligible.…”

Safety and Efficacy of Coronavirus Disease 2019 (COVID-19) mRNA Vaccines During Lactation

“…Breast-milk-derived SARS-CoV-2-specific antibodies have been detected in significant amounts in the breastfeeding infants' saliva and stool, 64,65,68 and studies performed in vitro support the capability of breast-milk-derived anti-SARS-CoV-2 IgG and secretory IgA to resist degradation in the infant gut. 69,70 Importantly, however, anti-SARS-CoV-2 antibodies have not been detected in the blood of infants whose mothers were vaccinated during lactation only, 29,68 suggesting that maternally derived antibodies from breast milk likely do not cross the gut mucosal barrier in detectable quantities. This stands in contrast to antibodies that are transplacentally transferred from mothers vaccinated during pregnancy, which are detectable in the infant's circulation for up to 6 months in the majority of cases.…”

Static in vitro digestion model adapted to the general older adult population: an INFOGEST international consensus

“…7 Static models mimicking the infant gastrointestinal tract have been proposed; [8][9][10][11] among those a model has been proposed as an international consensus by INFOGEST participants 12 and has been, since then, used in more than a hundred studies published by the scientific community. [13][14][15][16] Ageing is accompanied by several physiological changes that affect most of the organs of the human body. For example, due to decline in muscular function, impairment in dental status and reduction in salivary flow and modification in composition, there is impairment in oral processing capability which can alter particle size reduction, adversely affecting digestion rate and extent.…”

“…7 Static models mimicking the infant gastrointestinal tract have been proposed; 8–11 among those a model has been proposed as an international consensus by INFOGEST participants 12 and has been, since then, used in more than a hundred studies published by the scientific community. 13–16…”