SARS-CoV-2 RNA and antibody detection in breast milk from a prospective multicentre study in Spain

Arch Dis Child Fetal Neonatal Ed. 2022 Mar;107(2):216-221. doi: 10.1136/archdischild-2021-322463. Epub 2021 Aug 20.


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. Trial registration number NCT04768244.

Keywords: COVID-19; global health; microbiology; neonatology.

Publication types

  • Multicenter Study

MeSH terms

  • Adult
  • Antibodies, Viral / analysis
  • COVID-19 / epidemiology*
  • COVID-19 / immunology*
  • Coronavirus Envelope Proteins / analysis
  • Coronavirus Nucleocapsid Proteins / analysis
  • Female
  • Humans
  • Immunoglobulins / analysis
  • Longitudinal Studies
  • Milk, Human / immunology*
  • Phosphoproteins / analysis
  • Prospective Studies
  • RNA, Viral / analysis
  • SARS-CoV-2
  • Spain


  • Antibodies, Viral
  • Coronavirus Envelope Proteins
  • Coronavirus Nucleocapsid Proteins
  • Immunoglobulins
  • Phosphoproteins
  • RNA, Viral
  • envelope protein, SARS-CoV-2
  • nucleocapsid phosphoprotein, SARS-CoV-2

Associated data