Bauerl, ChristineRandazzo, WalterSanchez, GloriaSelma-Royo, MartaGarcia Verdevio, EliaMartinez, LauraParra-Llorca, AnnaLerin, CarlesFumado, VictoriaCrovetto, FrancescaCrispi, FatimaPerez-Cano, Francisco J.Rodriguez, GerardoRuiz-Redondo, GemmaCampoy, CristinaMartinez-Costa, CeciliaCarmen Collado, MariaMilkCORONA Study Team2025-01-072025-01-072021-08-191359-2998https://hdl.handle.net/10668/26065Objectives To develop and validate a specific protocol for SARS-CoV-2 detection in breast milk matrix and to determine the impact of maternal SARS-CoV-2 infection on the presence, concentration and persistence of specific SARS-CoV-2 antibodies. Design and patients This is a prospective, multicentre longitudinal study (April-December 2020) in 60 mothers with SARS-CoV-2 infection and/or who have recovered from COVID-19. A control group of 13 women before the pandemic were also included. Setting Seven health centres from different provinces in Spain. Main outcome measures Presence of SARS-CoV-2 RNA in breast milk, targeting the N1 region of the nucleocapsid gene and the envelope (E) gene; presence and levels of SARS-CoV-2-specific immunoglobulins (Igs)-IgA, IgG and IgM-in breast milk samples from patients with COVID-19. Results All breast milk samples showed negative results for presence of SARS-CoV-2 RNA. We observed high intraindividual and interindividual variability in the antibody response to the receptor-binding domain of the SARS-CoV-2 spike protein for each of the three isotypes IgA, IgM and IgG. Main Protease (MPro) domain antibodies were also detected in milk. 82.9% (58 of 70) of milk samples were positive for at least one of the three antibody isotypes, with 52.9% of these positive for all three Igs. Positivity rate for IgA was relatively stable over time (65.2%-87.5%), whereas it raised continuously for IgG (from 47.8% for the first 10 days to 87.5% from day 41 up to day 206 post-PCR confirmation). Conclusions Our study confirms the safety of breast feeding and highlights the relevance of virus-specific SARS-CoV-2 antibody transfer. This study provides crucial data to support official breastfeeding recommendations based on scientific evidence.ARS-CoV-2 antibodies but not RNA are found in breast milk from COVID-19 infected mothers.enAttribution-NonCommercial 4.0 Internationalhttp://creativecommons.org/licenses/by-nc/4.0/COVID-19microbiologyneonatologyglobal healthCovid-19research article34417223open access10.1136/archdischild-2021-3224631468-2052https://fn.bmj.com/content/fetalneonatal/107/2/216.full.pdf724314600001