Characterization of SARS-CoV-2 antibodies in human milk from 21 women with confirmed COVID-19 infection.

BACKGROUND: One potential mechanism for protection from SARS-CoV-2 in children is through passive immunity via breast milk from a mother infected with the novel coronavirus. The primary objectives of this study were to establish the presence of SARS-CoV-2-specific IgA and IgG and to characterize the antigenic regions of SARS-CoV-2 proteins that were reactive with antibodies in breast milk. METHODS: Between March 2020 and September 2020, 21 women with confirmed SARS-CoV-2 infection were enrolled in Mommy's Milk. Participants donated serial breast milk samples around their time of illness. Breast milk samples were used to probe a multi-coronavirus protein microarray containing full-length and variable-length overlapping fragments of SARS-CoV-2 proteins. Samples were also tested against S and N proteins by electrochemiluminescence assay. RESULTS: The breast milk samples contained IgA reactive with a variety of SARS-CoV-2 antigens. The most IgA-reactive SARS-CoV-2 proteins were N (42.9% of women responded to ≥1 N fragment) and S proteins (23.9% responded to ≥1 fragment of S1 or S2). IgG responses were similar. A striking observation was the dissimilarity between mothers in antibody recognition, giving distinct antibody reactivity and kinetic profiles. CONCLUSIONS: Individual COVID-19 cases had diverse and unique milk IgA profiles following the onset of symptoms. IMPACT: In this observational longitudinal case series of 21 women with confirmed SARS-CoV-2 infection, IgA binding to SARS-CoV-2 proteins detected by orthologous proteome microarray and electrochemiluminescence assays was observed in >75% of women, but there was heterogeneity in which antigens and how many were reactive between women. Immunological profiles of protein regions recognized by each woman were distinct. Diverse repertoires of mucosal breast milk antibody to SARS-CoV-2 reflect heterogeneous passive transfer of maternal antibody to exposed breastfeeding infants.

COVID-19 and Human Milk: Are We Prepared for the Next Pandemic?

For most babies, human milk is considered the best form of early life nutrition with additional immediate and long-term benefits for health and development. During extreme circumstances and crises, it is therefore of utmost importance to monitor and protect the safety of breastfeeding and the use of human milk. At the onset of the recent COVID-19 pandemic, it was critical to rapidly establish rigorous scientific evidence to ensure that the emerging infectious agent SARS-CoV-2 is not transmitted through human milk. As soon as the WHO declared COVID-19 a pandemic on 11 March 2020, we quickly assembled and activated a multidisciplinary team of human milk researchers and virologists and leveraged our existing Human Milk Research Biorepository to recruit lactating women and collect milk samples - literally from day 1 of the pandemic. We and others used RT-qPCR and found that human milk does indeed occasionally contain SARS-CoV-2 viral mRNA. However, a virus is more than a piece of mRNA, which alone is not able to cause the disease. We therefore tested the hypothesis that viral mRNA found in human milk represents an active, replication competent virus. We validated a cell culture SARS-CoV-2 infectivity assay for use in human milk and discovered the following: (i) the presence of SARS-CoV-2 mRNA in human milk of infected women is rare;(ii) The presence of viral RNA is not the same as presence of active, replication-competent virus. In fact, none of the human milk samples from SARS-CoV-2-infected women contained replication-competent virus, including samples that tested positive for viral mRNA by RT-qPCR;and (iii) even if human milk was contaminated with SARS-CoV-2 during pumping and handling, Holder pasteurization, which is commonly used by human milk banks, inactivates the virus in contaminated human milk. In summary, our research has provided scientific evidence that transmission of SARS-CoV-2 from mother to infant through breastfeeding and the use of human milk is highly unlikely. This study was officially published on 19 August 2020, 161 days after the WHO declared COVID-19 a pandemic. Under normal circumstances, this timeline from ideation to publication would be considered remarkably fast, but it wasn't fast enough during a time of crisis. A total of 161 days of uncertainty has led to fear-based confusion, misinformation, and increased the risk of breastfeeding cessation despite the well-documented benefits of human milk and breastfeeding. The current pandemic has uncovered the urgent and immediate need to invest in research that establishes the safety of breastfeeding and human milk at crisis onset. We therefore call on governments, public health agencies, and the scientific community at large to establish a 'rapid response task force';that is capable of rapidly and rigorously monitoring and assessing the safety of breastfeeding and human milk at the onset of the next global health crisis.

No infectious SARS-CoV-2 in breast milk from a cohort of 110 lactating women.

BACKGROUND: Genomic RNA of severe acute respiratory syndrome-associated coronavirus type 2 (SARS-CoV-2) has been detected in the breast milk of lactating women, but its pathological significance has remained uncertain due to the small size of prior studies. METHODS: Breast milk from 110 lactating women was analyzed by reverse transcription-polymerase chain reaction (285 samples) and viral culture (160 samples). Those containing SARS-CoV-2 viral RNA (vRNA) were examined for the presence of subgenomic RNA (sgRNA), a putative marker of infectivity. RESULTS: Sixty-five women had a positive SARS-CoV-2 diagnostic test, 9 had symptoms but negative diagnostic tests, and 36 symptomatic women were not tested. SARS-CoV-2 vRNA was detected in the milk of 7 (6%) women with either a confirmed infection or symptomatic illness, including 6 of 65 (9%) women with a positive SARS-CoV-2 diagnostic test. Infectious virus was not detected in any culture and none had detectable sgRNA. In control experiments, infectious SARS-CoV-2 could be cultured after addition to breastmilk despite several freeze-thaw cycles, as it occurs in the storage and usage of human milk. CONCLUSIONS: SARS-CoV-2 RNA can be found infrequently in the breastmilk after recent infection, but we found no evidence that breastmilk contains an infectious virus or that breastfeeding represents a risk factor for transmission of infection to infants. IMPACT: This article goes beyond prior small studies to provide evidence that infectious SARS-CoV-2 is not present in the milk of lactating women with recent infection, even when SARS-CoV-2 RNA is detected. Recent SARS-CoV-2 infection or detection of its RNA in human milk is not a contraindication to breastfeeding.

Promoting and Protecting Human Milk and Breastfeeding in a COVID-19 World.

The global COVID-19 pandemic has put enormous stress on healthcare systems and hospital staffing. However, through all this, families will continue to become pregnant, give birth, and breastfeed. Unfortunately, care of the childbearing family has been de-prioritized during the pandemic. Additionally, many healthcare practices during the pandemic have not been positive for the childbearing family or breastfeeding. Despite recommendations from the World Health Organization to promote early, direct breastfeeding and skin to skin contact, these and other recommendations are not being followed in the clinical setting. For example, some mothers have been forced to go through labor and birth alone in some institutions whilst some hospitals have limited or no parental visitation to infants in the NICU. Furthermore, hospitals are discharging mothers and their newborns early, limiting the amount of time that families receive expert lactation care, education, and technical assistance. In addition, some hospitals have furloughed staff or transferred them to COVID-19 wards, further negatively impacting direct care for families and their newborns. We are concerned that these massive changes in the care of childbearing families will be permanently adopted. Instead, we must use the pandemic to underscore the importance of human milk and breastfeeding as lifesaving medical interventions. We challenge healthcare professionals to change the current prenatal and post-birth practice paradigms to protect lactation physiology and to ensure that all families in need receive equal access to evidence-based lactation education, care and technical assistance.

SARS-CoV-2 and human milk: What is the evidence?

The novel coronavirus SARS-CoV-2 has emerged as one of the most compelling and concerning public health challenges of our time. To address the myriad issues generated by this pandemic, an interdisciplinary breadth of research, clinical and public health communities has rapidly engaged to collectively find answers and solutions. One area of active inquiry is understanding the mode(s) of SARS-CoV-2 transmission. Although respiratory droplets are a known mechanism of transmission, other mechanisms are likely. Of particular importance to global health is the possibility of vertical transmission from infected mothers to infants through breastfeeding or consumption of human milk. However, there is limited published literature related to vertical transmission of any human coronaviruses (including SARS-CoV-2) via human milk and/or breastfeeding. Results of the literature search reported here (finalized on 17 April 2020) revealed a single study providing some evidence of vertical transmission of human coronavirus 229E; a single study evaluating presence of SARS-CoV in human milk (it was negative); and no published data on MERS-CoV and human milk. We identified 13 studies reporting human milk tested for SARS-CoV-2; one study (a non-peer-reviewed preprint) detected the virus in one milk sample, and another study detected SARS-CoV-2 specific IgG in milk. Importantly, none of the studies on coronaviruses and human milk report validation of their collection and analytical methods for use in human milk. These reports are evaluated here, and their implications related to the possibility of vertical transmission of coronaviruses (in particular, SARS-CoV-2) during breastfeeding are discussed.