Abstract
SARS-CoV-2-specific antibodies are secreted into human milk of infected or vaccinated lactating women and might provide protection to the breastfed infant against COVID-19. Differences in antibody response after these types of exposure are unknown. In this longitudinal cohort study, we compared the antibody response in human milk following SARS-CoV-2 vaccination or infection. We analyzed 448 human milk samples of 28 lactating women vaccinated with the SARS-CoV-2 vaccine BNT162b2 as well as 82 human milk samples of 18 lactating women with a prior SARS-CoV-2 infection. The levels of SARS-CoV-2-specific IgA in human milk were determined over a period of 70 days both after vaccination and infection. The amount of SARS-CoV-2-specific IgA in human milk was similar after SARS-CoV-2 vaccination and infection. After infection, the variability in IgA levels was higher than after vaccination. Two participants with detectable IgA prior to vaccination were analyzed separately and showed higher IgA levels following vaccination compared to both groups. In conclusion, breastfed infants of mothers who have been vaccinated with the BNT162b2 vaccine receive human milk with similar amounts of SARS-CoV-2-specific antibodies compared to infants of previously infected mothers.
Highlights
The clinical presentation of severe acute respiratory syndrome coronavirus (SARSCoV-2) in infected children seems to be mild; severe coronavirus disease 2019 (COVID-19) has been reported in infants including cases of mechanical ventilation, liver and cardiac function impairment, and even death [1,2,3,4]
Human milk samples were collected from 46 lactating women, of whom 28 received the mRNA-based COVID-19 vaccine BNT162b2 and 18 had a prior Polymerase Chain Reaction (PCR)-confirmed SARSCoV-2 infection (Figure 1)
Consistent with previous reports [21], we found high variability in human milk SARSCoV-2-specific Immunoglobulin A (IgA) levels in previously infected participants, with some of them having no milk conversion over the entire study period
Summary
The clinical presentation of severe acute respiratory syndrome coronavirus (SARSCoV-2) in infected children seems to be mild; severe coronavirus disease 2019 (COVID-19) has been reported in infants including cases of mechanical ventilation, liver and cardiac function impairment, and even death [1,2,3,4]. Based on a recent analysis of 576 SARS-CoV-2-infected children, infants seem to be more vulnerable to severe disease relative to older children [6]. They might be partially protected via human milk, as human milk contains several immune-enhancing factors, including antibodies, oligosaccharides, nucleic acids, and cytokines [7]. The ability to neutralize SARS-CoV-2 is directly associated with levels of IgA against the receptorbinding domain of the viral surface spike (S) protein [13] These neutralizing human milk antibodies may play an important role in protecting the breastfed infant against COVID-19
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