Mothers with two types of immunity from COVID — disease-acquired (those who have contracted COVID and recovered) and vaccination-acquired — produced breast milk with active SARS-CoV-2 antibodies, found a study co-authored by researchers at the University of Rochester Medical Center and New York University in published in JAMA Pediatrics.
Entitled Comparison of human milk antibody induction, persistence, and neutralising capacity in response to SARS-CoV-2 infection versus mRNA vaccination, the study was funded by the National Institute of Allergy and Infectious Diseases (NIAID) with support from Medela LLC.
Samples were collected from 77 mothers, 47 in the infected group, 30 in the vaccine group, to determine the level of antibodies in breast milk over time. Mothers who had disease-acquired immunity produced high levels of Immunoglobulin A (IgA) antibodies against the virus in breast milk, while vaccine-acquired immunity produced robust Immunoglobulin G (IgG) antibodies.
Both antibodies provided neutralisation against SARS-CoV-2, the first time such evidence has been discovered for both IgA and IgG antibodies, according to study co-author Bridget Young, assistant professor in the Division of Pediatric Allergy and Immunology at URMC.
“It’s one thing to measure antibody concentrations, but it’s another to say that antibodies are functional and can neutralise the SARS-CoV-2 virus," said Young,
“One of the exciting findings in this work is that breast milk from both mothers with COVID-19 infection, and from mothers receiving mRNA vaccination contained these active antibodies that were able to neutralise the virus.”
Previous studies from URMC had shown evidence of antibodies in breast milk from COVID-positive mothers. This follow-up study represents the longest time period that disease-acquired antibodies have been examined post-illness, and the results showed that these antibodies exist for three months after infection.
For vaccinated mothers, the study found evidence of a mild-to-modest decline in antibodies, on average three months post-vaccination.
“The trend in breast milk antibodies aligns with what we see in vaccination sera,” said study co-author Dr Kirsi Jarvinen-Seppo, chief of Pediatric Allergy and Immunology at URMC. “After a few months, the antibodies trend downward, but the levels are still significantly above what they were pre-vaccine.”
Both Young and Jarvinen-Seppo emphasise, however, that while the antibody response exists, it’s not yet shown whether these breast milk antibodies can provide protection against COVID for nursing children.
“The study does not imply that children would be protected from illness,” said Jarvinen-Seppo, “and breast milk antibodies may not be a substitute for vaccination for infants and children, once approved.”
For the next phase of the study, URMC researchers are looking to find evidence whether both vaccination and illness-acquired immunity provide antibodies against other seasonal coronaviruses.
Study details
Association of Human Milk Antibody Induction, Persistence, and Neutralizing Capacity With SARS-CoV-2 Infection vs mRNA Vaccination.
Bridget E. Young, Antti E. Seppo, Nichole Diaz, Casey Rosen-Carole, Anna Nowak-Wegrzyn, Joseline M. Cruz Vasquez, Rita Ferri-Huerta, Phuong Nguyen-Contant, Theresa Fitzgerald, Mark Y. Sangster, David J. Topham, Kirsi M. Järvinen.
Published in JAMA Pediatrics on 10 November 2021
Key Points
Question How does human milk antibody composition and neutralisation activity differ between lactating parents with COVID-19 infection vs those with COVID-19 messenger RNA vaccination?
Findings In this cohort study of a convenience sample of 47 lactating parents with infection and 30 lactating parents who were vaccinated, antibody response in milk after infection was IgA dominant and highly variable while vaccination was associated with a robust IgG response, which began to decline by 90 days after the second vaccine dose. Milk from both groups showed neutralisation activity against live SARS-CoV-2 virus, which can be attributed to IgA and IgG SARS-CoV-2 antibodies.
Meaning COVID-19 infection and vaccination may result in significant antibodies in human milk that exhibit different temporal patterns, but both neutralise live SARS-CoV-2 virus.
Abstract
Importance
Long-term effect of parental COVID-19 infection vs vaccination on human milk antibody composition and functional activity remains unclear.
Objective
To compare temporal IgA and IgG response in human milk and microneutralisation activity against SARS-CoV-2 between lactating parents with infection and vaccinated lactating parents out to 90 days after infection or vaccination.
Design, Setting, and Participants
Convenience sampling observational cohort (recruited July to December 2020) of lactating parents with infection with human milk samples collected at days 0 (within 14 days of diagnosis), 3, 7, 10, 28, and 90. The observational cohort included vaccinated lactating parents with human milk collected prevaccination, 18 days after the first dose, and 18 and 90 days after the second dose.
Exposures
COVID-19 infection diagnosed by polymerase chain reaction within 14 days of consent or receipt of messenger RNA (mRNA) COVID-19 vaccine (BNT162b2 or mRNA-1273).
Main Outcomes and Measures
Human milk anti–SARS-CoV-2 receptor-binding domain IgA and IgG and microneutralisation activity against live SARS-CoV-2 virus.
Results
Of 77 individuals, 47 (61.0%) were in the infection group (mean [SD] age, 29.9 [4.4] years), and 30 (39.0%) were in the vaccinated group (mean [SD] age, 33.0 [3.4] years; P = .002). The mean (SD) age of infants in the infection and vaccinated group were 3.1 (2.2) months and 7.5 (5.2) months, respectively (P < .001). Infection was associated with a variable human milk IgA and IgG receptor-binding domain–specific antibody response over time that was classified into different temporal patterns: upward trend and level trend (33 of 45 participants [73%]) and low/no response (12 of 45 participants [27%]).
Infection was associated with a robust and quick IgA response in human milk that was stable out to 90 days after diagnosis. Vaccination was associated with a more uniform IgG-dominant response with concentrations increasing after each vaccine dose and beginning to decline by 90 days after the second dose. Vaccination was associated with increased human milk IgA after the first dose only (mean [SD] increase, 31.5 [32.6] antibody units). Human milk collected after infection and vaccination exhibited microneutralisation activity.
Microneutralisation activity increased throughout time in the vaccine group only (median [IQR], 2.2 [0] before vaccine vs 10 [4.0] after the first dose; P = .003) but was higher in the infection group (median [IQR], 20 [67] at day 28) vs the vaccination group after the first-dose human milk samples (P = .002). Both IgA and non-IgA (IgG-containing) fractions of human milk from both participants with infection and those who were vaccinated exhibited microneutralisation activity against SARS-CoV-2.
Conclusions and Relevance
In this cohort study of a convenience sample of lactating parents, the pattern of IgA and IgG antibodies in human milk differed between COVID-19 infection vs mRNA vaccination out to 90 days. While infection was associated with a highly variable IgA-dominant response and vaccination was associated with an IgG-dominant response, both were associated with having human milk that exhibited neutralisation activity against live SARS-CoV-2 virus.
See more from MedicalBrief archives:
Pfizer/Moderna vaccine side effects in breastfeeding women and infants
Pregnant women pass COVID antibodies to their babies — Weill Cornell
J&J roll-out falters again despite SAHPRA clearing jab for pregnant women