BACKGROUND AND PURPOSE:

• Case reports have documented viral RNA in breast milk samples
  • Unclear as to source of virus
  • Presence of viral RNA does not necessarily mean infectious virus is present
• Chambers et al. (JAMA, 2020) examined breast milk samples from COVID-19 mothers to determine if viral RNA and/or replication-competent virus was present

METHODS:

• Cohort study (March 27 and May 6, 2020)
• Participants
  • Women who were breastfeeding
  • RT-PCR confirmed COVID-19 diagnosis
• Study design
  • Women invited to participate through media awareness, website, and clinician referral
  • Breast milk sampled were self-collected and mailed to the study center
  • Samples tested with
    • Quantitative RT-PCR assay for SARS-CoV-2
    • Cell culture assay to determine presence of replication-competent virus
  • The authors also added SARS-CoV-2 to pasteurized and nonpastuerized breast milk from control donors

RESULTS:

• A total of 18 breastfeeding women with COVID-19 were enrolled
  • Mean (SD) age: 34.4 (5.2) years
  • Offspring ranged in age from newborn to 19 months
  • Total 64 total samples | Women provided between 1 and 12 samples
• One breast milk sample had detectable levels of SARS-CoV-2 RNA
  • This sample was collected on the day of symptom onset
  • A sample from this same participant taken 2 days prior to symptom onset and two samples take 12 and 41 days after onset tested negative
  • The breastfed infant was not tested
• No replication-competent virus found in any sample
• Following pasteurization, viral RNA was not detectable by RT-PCR in the samples that had been spiked with SARS-CoV-2
  • The virus was detected in the nonpasteurized samples

CONCLUSION:

• Out of 64 breast milk samples, viral RNA was found in only 1 sample
  • The viral RNA did not represent replication-competent virus
• When breast milk samples spiked with SARS-CoV-2 were pasteurized, no replication-competent virus or viral RNA was detectable | Reassuring regarding human milk available through milk banks
• Limitations
  • Small sample size and nonrandom sampling
  • Self-collection of milk samples
• The authors state

These data suggest that SARS-CoV-2 RNA does not represent replication-competent virus and that breast milk may not be a source of infection for the infant

Learn More – Primary Sources:

Evaluation for SARS-CoV-2 in Breast Milk From 18 Infected Women

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