SARS-CoV-2 RNA and antibody detection in breast milk from a prospective multicentre study in Spain Bäuerl, Christine Ruiz Redondo, Gemma Campoy Folgoso, Cristina MilkCORONA COVID-19 Microbiology Neonatology Global health This study has been supported by a research grant from Fundacion La Marato-TV3 (MilkCORONA, ref 202106). Objectives 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. 2021-12-13T08:56:40Z 2021-12-13T08:56:40Z 2021-08-20 info:eu-repo/semantics/article Bäuerl C... [et al.]. SARS-CoV-2 RNA and antibody detection in breast milk from a prospective multicentre study in SpainArchives of Disease in Childhood - Fetal and Neonatal Edition Published Online First: 20 August 2021. doi: [10.1136/archdischild-2021-322463] http://hdl.handle.net/10481/72030 10.1136/archdischild-2021-322463 eng http://creativecommons.org/licenses/by-nc/3.0/es/ info:eu-repo/semantics/openAccess Atribución-NoComercial 3.0 España BMJ