Comparing the SARS-CoV-2-specific antibody response in human milk after homologous and heterologous booster vaccinations

• Published in: Communications biology Vol. 6; no. 1; p. 100
• Main Authors: Mulleners, Sien J, Juncker, Hannah G, Ruhé, Eliza J M, Korosi, Aniko, van Goudoever, Johannes B, van Gils, Marit J, van Keulen, Britt J
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 25.01.2023; Nature Publishing Group UK; Nature Portfolio
• Subjects: Antibodies; Antibodies, Viral; Antibody Formation; Antibody response; Biology; Breast milk; Coronaviruses; COVID-19; COVID-19 - prevention & control; COVID-19 Vaccines; Female; Follow-Up Studies; Humans; Immunity (passive); Immunoglobulin A; Immunoglobulin G; Immunoglobulins; Infant; Lactation; Milk, Human; mRNA; Prospective Studies; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Vaccines
• ISSN: 2399-3642; 2399-3642
• DOI: 10.1038/s42003-023-04455-4

Human milk contains SARS-CoV-2-specific antibodies after COVID-19 vaccination. These milk antibodies decrease several months post-vaccination. Whether booster immunization restores human milk antibody levels, potentially offering prolonged passive immunity for the infant, remains unknown. In this prospective follow-up study, we investigated the longitudinal SARS-CoV-2-specific antibody response in human milk of 26 lactating women who received a COVID-19 booster dose of an mRNA-based vaccine. Moreover, we evaluated whether the booster-induced human milk antibody response differs for participants who received a similar or different vaccine type in their primary vaccination series. All participants (100%) who received a homologous booster vaccination showed SARS-CoV-2-specific immunoglobulin A (IgA) and immunoglobulin G (IgG) in their milk. Heterologous booster vaccination resulted in milk conversion for 9 (69%) and 13 (100%) participants for IgA and IgG respectively. Findings of this study indicate that both homologous and heterologous boosting schedules have the potential to enhance SARS-CoV-2-specific IgA and IgG in human milk.