Abstract
The appearance of the severe acute respiratory syndrome virus-2 (SARS-CoV-2) has had a significant impact on the balance of public health and social life. The data available so far show that newborns and young children do not develop severe forms of COVID-19, but a small proportion of them will still need hospitalization. Even though young children represent an important vector of the infection, vaccination at such a young age was not yet considered. Thus, the question of whether potentially protective antibodies against SARS-CoV-2 could be provided to them via breast milk or across the placenta, as “passive immunity”, still stands. Materials and Methods: Between January–July 2021, we have conducted a prospective study that aimed to measure the immunoglobulin (Ig) A and IgG anti-SARS-CoV-2 titers in the breast milk of 28 vaccinated lactating mothers, sampled at 30 and 60 days after the second dose of the anti-SARS-CoV-2 Pfizer or Moderna mRNA vaccines. Anti-RBD reactive IgA and IgG antibodies were detected and quantified by a sandwich enzyme-linked immunosorbent assay. Results: Anti-RBD IgA and IgG were present in all breast milk samples, both in the first and in the second specimens, without a significant difference between those two. The anti-RBD IgA titers were approximately five-times higher than the anti-RBD IgG ones. The anti-RBD IgA and IgG titers were correlated with the infants’ age, but they were not correlated with the vaccine type or mother’s age. The anti-RBD IgA excreted in milk were inversely correlated with the parity number. Conclusions: Anti-SARS-CoV-2 IgA and IgG can be found in the milk secretion of mothers vaccinated with mRNA vaccines and, presumably, these antibodies should offer protection to the newborn, considering that the antibodies’ titers did not decrease after 60 days. The antibody response is directly proportional to the breastfed child’s age, but the amount of anti-RBD IgA decreases with the baby’s rank. The antibody response did not depend on the vaccine type, or on the mother’s age.
Highlights
IntroductionIt was shown that the SARS-CoV-2 infection leads to an immune response that generates neutralizing antibodies which target the receptor-binding domain or other regions of the protein [2,3,4]
The appearance of the severe acute respiratory syndrome virus-2 (SARS-CoV-2)changed the path of our lives, having a significant impact on the balance of public health and social life [1].It was shown that the SARS-CoV-2 infection leads to an immune response that generates neutralizing antibodies which target the receptor-binding domain or other regions of the protein [2,3,4]
The aim of our study was to detect the presence of anti-SARS-CoV-2 IgA and immunoglobulins G (IgG) in human breast milk, to measure their concentrations, and to assess if any of the features considered for the characterization of our volunteers might influence the milk antibody titers
Summary
It was shown that the SARS-CoV-2 infection leads to an immune response that generates neutralizing antibodies which target the receptor-binding domain or other regions of the protein [2,3,4]. COVID-19 vaccines are shown to be effective against severe disease, including those caused by the Delta [8] variant and, to a certain level, the Omicron variant [9]. The results of the clinical trials for the two available mRNA anti-SARS-CoV-2 vaccines became readily available. The Pfizer BNT162b1 vaccine was the first to demonstrate its ability to mount both a T helper 1 immune response and a humoral one [10], followed by the results demonstrating that the Moderna vaccine is at least effective in terms of efficacy and safety [11] or antibody production [12]. Many more studies supported these data, some pointing out the production of both immunoglobulins G (IgG) and A (IgA) in the serum of vaccinated adults [13]
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