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Antibodies Against SARS-CoV-2 in Human Breast Milk After Vaccination: A Systematic Review and Meta-Analysis
Noah Whited1, Jorge Cervantes1
1Paul L. Foster School of Medicine, Texas Tech University Health Science Center, El Paso, Texas, USA.
Insights
COVID-19 vaccination in breastfeeding mothers leads to antibodies in breast milk. High rates of IgA and IgG antibodies were found after vaccination, offering potential protection for infants.
Area of Science:
- Immunology
- Vaccinology
- Public Health
Background:
- The U.S. Centers for Disease Control and Prevention (CDC) recommends COVID-19 vaccination for individuals aged 5 and older, including breastfeeding mothers.
- Breast milk is a crucial source of passive immunity for neonates, particularly those with immature immune systems.
- Maternal vaccination has been demonstrated to induce antibody transfer into breast milk.
Purpose of the Study:
- To systematically review and meta-analyze the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in human breast milk following COVID-19 vaccination.
- To quantify the rates of immunoglobulin A (IgA) and immunoglobulin G (IgG) antibodies in breast milk post-vaccination.
Main Methods:
- A systematic literature search was conducted across PubMed, Embase, and Web of Science for studies published between December 1, 2019, and September 30, 2021.
- Included studies evaluated immunoglobulins in breast milk from women who received a SARS-CoV-2 vaccination.
- Data extraction included antibody levels and peak days, with additional information provided by corresponding authors.
Main Results:
- The review identified 18 cohort studies from an initial 192 articles.
- Following the first vaccine dose, 64% of breast milk samples were positive for IgA and 30% for IgG.
- After the second vaccine dose, positivity rates increased to 70% for IgA and 91% for IgG.
Conclusions:
- Worldwide data indicate a high prevalence of SARS-CoV-2 antibodies in breast milk after COVID-19 immunization.
- Further research is needed to determine the persistence of these antibodies and their efficacy in preventing infant SARS-CoV-2 infections.
Abstract:
Background: CDC guidelines have recommended coronavirus disease-19 (COVID-19) vaccination for all people 5 years and older, including people who are breastfeeding. Breast milk has shown to be a valuable source of protection for immune-immature neonates. It has been shown that breast milk from mothers who have received vaccinations can transfer antibodies. Aim/Objective: This systematic review and meta-analysis investigate the presence of antibodies to SARS-CoV-2 in human breast milk after vaccination. Methods: Studies that evaluated immunoglobulins in breast milk of women receiving a SARS-CoV-2 vaccination were included. PubMed, Embase, Web of Science were searched for articles published between December 1, 2019 and September 30, 2021. Data from relevant articles were extracted manually or by WebPlotDigitizer version 4.1 to obtain the numeric values of antibody levels on peak days and the peak day then condensed into Excel. Additional raw data and information were supplied by corresponding authors. Results: One hundred ninety-two articles were obtained from the search. After excluding duplicates, screening titles and abstracts, 18 cohort studies were identified. For the rate of SARS-CoV-2 antibodies in breast milk after the first vaccine dose but before the second vaccine dose, we found 64% (95% CI 51-78%) were positive for IgA and 30% (95% CI 13.1-46%) were positive for IgG. For the rate for SARS-CoV-2 antibodies in breast milk after the second vaccine dose, we found 70% (95% CI 55-86%) were positive for IgA and 91% (95% CI 80-103%) were positive for IgG. Conclusions: Our analysis of the data published worldwide showed high rates of positivity for antibodies in breast milk following COVID-19 immunizations. Further research is necessary to find if the rate of positivity of IgA and IgG against SARS-CoV-2 in breast milk persists months after the full immunization, and their impact on the prevention of SARS-CoV-2 infection in infants.
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