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

Our take —

This study aimed to assess the presence of SARS-CoV-2 in breastmilk to evaluate the potential for transmission via breastfeeding. The study was conducted with 18 women who were breastfeeding and who self-reported having a confirmed SARS-CoV-2 RT-PCR test. Women provided mail in samples of breast milk which were self-collected. Samples were tested for SARS-CoV-2. Evidence of SARS-CoV-2 RNA was detected in one breast milk sample (1/18 women and 1/64 samples). The positive test result was collected on the day of symptom onset. No replication-competent virus was detectable in any sample. This study is subject to several limitations relating to unconfirmed diagnosis of participants, specimen collection, and sample size. Importantly, limited detail on clinical presentation and testing histories, and inconsistent timing of sample collection may greatly limit the findings of this study. The study suggests that breastmilk may not create substantial risk of transmission, however timing of sample collection and transport limit the possible conclusions.

Study design

Case Series

Study population and setting

This study included 18 women who were breastfeeding and who self-reported having a confirmed SARS-CoV-2 RT-PCR test. Women who were residing in the US were recruited through media awareness, website, and clinician referral. Clinical data were collected via phone interviews, and women provided self-collected breast milk samples which were mailed to the study center. Breast milk samples were tested using a validated RT-PCR assay and tissue culture methods to detect replication-competent SARS-CoV-2 in breast milk were used. A total of 64 breast milk samples were collected, with women providing between 1 and 12 samples each.

Summary of Main Findings

Evidence of SARS-CoV-2 RNA was detected in one breast milk sample (1/64) from a single woman (1/18, 5.6%). The positive test result was collected on the day of symptom onset. No replication-competent virus was detectable in any sample.

Study Strengths

Multiple samples were collected from some women in the study.

Limitations

This study may be subject to information bias, as participants self-reported positive RT-PCR testing results for SARS-Cov-2. This study provides limited detail on clinical presentation and testing histories, such as symptom onset. Breast milk samples were not collected in a uniform manner, and the timing of sample collection was not consistent among women. The timing of sample collection over the course of infection may influence the results observed. This study was conducted with a small sample size limiting the ability to make inferences about the findings. Recruitment was conducted through a wide variety of mechanisms and may be subject to selection bias.

Value added

This study was innovative in its research question in that it aimed to assess the potential for transmission of SARS-Cov-2 via breast milk.

This review was posted on: 9 October 2020